Interaction Engineering · 4 / 10

Flow Restraint: Every Extra Step Drops Another Batch

Last lesson tamed dangerous buttons. This one looks at the whole path: from entry to done, how many steps are serving the software instead of the user's job. AI-generated flows share a disease: they're too complete. Be a flow auditor for once—cut a five-step signup to two.

ExciseCut stepsFunnel simOrchestration & flow
Work that gets you nowhere—Cooper named it

About Face 4, chapter 12, splits what users do into two kinds. One advances the goal directly—pressing the gas and steering on the drive to work. The other serves the tool: opening the garage, warming the engine, waiting at lights—none of which gets you closer to the office. That second kind Cooper calls excise.

In software, excise looks like this: you want to post an update, but first you log in, find the entry, dismiss a coachmark, and clear an upgrade dialog. Posting is the goal; the first four steps are tax. Cooper splits that tax into four kinds:

Cognitive tax
Figuring out how the product works: what buttons mean, how it's structured.
Memory tax
Memorizing passwords, commands, which menu level things live on.
Visual tax
Searching the screen: where eyes should start, what's clickable, what's decoration.
Physical tax
Clicks, travel, IME switching, the hand-work of navigating layer by layer.
"Eliminate every kind of excise as much as possible."
Alan Cooper lists this as a design principle, then sharpens it: excise in the UI is users' number-one reason for hating software.

One test—easy to remember: If you delete this step, can the user still reach the goal? If yes, it's excise. Bring that test to AI-delivered flows.

AI loves handing over "complete" flows—completeness is its disease

Ask AI for a signup page and it'll likely give you a five-step wizard: email, phone verification, profile, interest tags, confirm—nothing missing. It's seen too many "proper" signup flows in training data, so it serves the fullest set. Each step looks reasonable alone; together they're a tax corridor.

Cooper was never kind to wizards: they freeze the process into Q&A, and users quickly learn to tap "Next" with their brain offline. His alternative: just do the job, back it with sensible defaults, and let users change later. In the AI era, you have to write that into the brief—it won't think of it alone.

Before you cut, learn the faces. Of the excise sources chapter 12 names, three show up densest in AI output. Open each card for symptoms and the brief you give AI:

Three excise sources, quick lookup Opened 0 / 3
Navigation excise Open
Symptoms Page hops, window hops, digging through menus. Users are in a hurry; there's no scenery on the road—every step spends patience.
Typical AI disease One feature, one new page—even editing a nickname takes three hops; everyday tools buried in a submenu.
Brief for AI: finish everyday actions in place—don't open a new page; navigation at most two levels deep.
Interruption excise Open
Symptoms Confirm boxes, success dialogs, trivial reports—yanking people out of doing the job to serve the software.
Typical AI disease Every save pops "Saved successfully"—you must dismiss Confirm before you can keep working.
Brief for AI: use in-page light feedback; reserve dialogs for irreversible big deals.
Re-entry excise Open
Symptoms Making users report what the software already knows: log in again, fill the form again, reset preferences every time.
Typical AI disease Form submit fails; come back and everything you typed is gone.
Brief for AI: remember what was filled; on error keep the filled fields; give defaults you can infer.
Try it · Excise auditor: five-step signup cut to two

Below is an AI-generated membership signup—all five steps. The funnel on the right assumes 78% pass per step: 1,000 people enter, 289 finish five steps. Use the test and audit step by step—cut steps that aren't advancing the goal. Cut right and the funnel rises; cut wrong and it tells you why that one must stay.

Flow audit: keep what must stay, cut the rest Cut 0 / 3
Tap "Cut" on the right of each step. Cut steps collapse away; the funnel recalculates live
signup.example.com/register
Create accountFlow audit mode
1 Email and passwordEnter your usual email and set a login password
2 Phone verificationEnter phone number and a 6-digit SMS code
3 Complete your profileUpload avatar, fill nickname and birthday
4 Pick interest tagsChoose at least 5 for content recommendations
5 Agree and createCheck the terms, tap "Create account"
This flow's funnel
1,000 people tapped "Sign up"
Finished signup: 289 people
Demo model: 78% pass rate per step
Zoom out · Every extra step, how many drop

Signup is just the easiest example to count. Orders, publishing, registration, tickets—wherever there's a flow, this funnel shows up. Drag the slider to change step count and watch finishers move. A 22% drop-off is demo math only; real numbers vary by product, but the direction never flips: steps and retention move opposite ways.

Step-funnel simulator Drag slider
The flowing stripes in the funnel are demo animation—only play in viewport; you can pause
5 steps
1,000 enter; 289 finish
Orchestration and flow: a good flow keeps people in the zone

Cutting steps has theory behind it. About Face 4, chapter 11, covers "flow": Mihaly Csikszentmihalyi's idea that deep focus puts people in a high-output state where time disappears. Cooper's corollary: interaction design's job is to protect that state. Good interaction should be "transparent"—users face the job itself and barely feel the software.

Flow's enemy is interruption. Every extra step, every dialog, every page hop pulls users out of the zone—and getting back takes a warm-up. That's why funnels drop people: drop-off often happens at the interrupt, when someone looks up and thinks "why am I filling this?" and closes the page.

"No matter how cool the UI, less is better."
Alan Cooper, About Face 4, ch. 11. Same chapter, even more direct: don't stupidly interrupt the process.

Walkthrough for accepting AI output: run the core flow yourself end to end. At each step ask two things. First: if I delete this step, can the goal still be reached? Second: did this step yank me out of the zone? Only flows that pass both deserve to ship.

Quiz · Which step is excise

Warm up on a food-delivery checkout. One of four steps is classic excise—use the test to pick it.

Four steps to order delivery—which one collects tax? Single choice
Wrong answers come with explanations; keep going until you're right
ABrowse the menu and add dishes to the cart
BEnter a delivery address on the first order
CBefore every order submit, re-check "I have read and agree to the delivery terms"
DChoose a payment method and pay
Key Takeaways

Excise in one test: If you delete this step, can the user still reach the goal? If yes, it's excise (Cooper, About Face 4, ch. 12). Cognitive, memory, visual, physical—clear all four taxes.

Know the three excise faces: navigation (page hops, menus), interruption (dialogs and reports), re-entry (reporting what software already knows). AI output usually has all three—waiting for you to name and cut them.

Steps and retention move opposite ways: cut five-step signup to two and finishers double. Drop-off often sits at the interrupt; a good flow keeps people in the zone (ch. 11, orchestration and flow).

Brief for AI: "Signup only takes email and password; fill the rest after they're in the product; use in-page light feedback; remember filled fields." Once the flow is under control, next lesson covers how AI-invented new interactions trip users.

Source: Original to Xiaoshan Academy's Interaction Engineering series; some principles adapted from About Face 4: The Essentials of Interaction Design.