A purchasing approval process that takes days controls only the purchases somebody was willing to wait days for. Everything urgent goes on a card, arrives without an order, and is approved after the fact when refusal is no longer possible. That makes elapsed time a control metric rather than a convenience one, which is not how most approval processes are designed.
Design for the common case
Most requests are routine and small. Route them to one named approver with a visible threshold, cover during absence and escalation after a set period. Reserve multiple signatures for genuinely large commitments. Approval matrices that treat every request as potentially significant produce delay on the many to control the few.
Publish the thresholds
A requester who knows in advance what their request will need plans for it. One who discovers afterwards experiences the process as arbitrary and starts splitting requests to stay under limits, which is exactly the behaviour thresholds exist to prevent. Publishing costs nothing and removes most of the friction.
Measure adoption, not compliance
The honest measure is the share of invoices arriving with a purchase order behind them, month by month, by department. That number tells you how much spend the process actually controls. A rising figure is proof the control is spreading; a falling one is a warning long before anybody complains.
Questions people ask about purchasing approval process
How fast is fast enough?
Faster than the workaround available to your staff. If a card purchase takes an hour, a three-day approval will be bypassed for anything urgent.
Should urgent purchases have a route?
Yes, documented, with a named approver and a review afterwards. Undocumented emergency routes leave no record.
Does enforcement work?
Only once the process is fast enough to comply with. Enforcing a slow process produces resentment and creative workarounds.