Fixed-bid discovery turns the first invoice into a wager: the estimate is a guess about scope, the reconciliation is a negotiation about the guess, and every status email reopens both. Time-and-materials skips the guess but replaces it with an hourly meter somebody has to audit line by line. A subscription that states a 72-hour turnaround on one active request at a time is stating something stricter than either: a ceiling each request has to fit, set before any work starts, visible to both sides on the same board.

The ceiling matters most when a request outgrows it. On time-and- materials, growth becomes a longer invoice line discovered at month end. On a fixed bid, it becomes a change-order form. On a Requests -> Active -> Approved board, it becomes visible the day it happens: a card that cannot ship in three days of builder time is a scoping problem, and scoping has a dedicated move. The part that fits the 72-hour shape ships on schedule, and the remainder goes back to Requests as a new card the buyer ranks themselves. The delivery date survives and the reconciliation meeting never gets scheduled. Priority reordering costs nothing, because the flat fee never meters the queue; silent overrun is what cannot happen.

Bounded builder-time covers real deliverables, not slices, when the work is Python-first: a scraper with proxy rotation and structured output, an ETL pipeline that lands clean tables, a Django or FastAPI backend with authentication, an automation that glues three APIs into one workflow. What it does not cover in a single card is a migration plus a rewrite plus a replatform, and the ceiling never pretends otherwise; that is three cards, and the buyer ranks them. Slicing ambition into card-sized deliverables is not a downgrade. It is the difference between finished code landing in a private repo the buyer owns every week and everything landing after a phase-gate review, which is also the difference between a backlog that drains and one that ossifies.

the 72-hour turnaround, stated up front as a scope ceiling sits on Poket Dev's plans page next to the flat monthly price, and the one-active-card subscription with an unlimited queue is the same model from the buyer's side: reorder the queue whenever priorities move, cancel anytime, keep every line already shipped.