There is one number that determines whether purchase request software succeeds, and it is not a feature: how long a requester waits for an answer. Below a day, people use the process because it is easier than negotiating informally. Above a few days, they find another way to buy, and every control the software was bought to provide stops applying to that spend.
What actually creates the wait
Not the decision, which takes a minute. The wait is the request sitting with the wrong person, or with an approver who is away, or in a queue nobody owns. Products differ mainly in how well they handle those three, and none of them are prominent in a feature comparison because they sound like configuration rather than capability.
What to ask a vendor
What happens when an approver does nothing for a week. What happens when an approver is on leave and has not set a delegate. Where a request goes when the routing rules do not match. These three questions describe the cases that generate all the delay, and the answers are usually more revealing than any demonstration.
Measure it after implementation
Elapsed time to decision, as a distribution rather than an average, reviewed monthly. The tail will point at specific approvers, specific categories or specific rules, and each is a concrete fix. Also track the share of invoices arriving with a purchase order behind them, which is the independent proof that the process is spreading rather than being bypassed.
Questions people ask about purchase request software
What is a good target?
Same working day for routine requests is achievable in most organisations with delegation and escalation configured. Set the target and then look at what stops you meeting it.
Does adding approvers add control?
It adds delay reliably and control only sometimes. Two approvers each assuming the other looked properly is a documented failure pattern.
Should urgent requests bypass the system?
Have an explicit fast path inside it, reviewed afterwards. Bypasses that live outside the system leave no record at all.