The buyer-action rule
Every exit criterion should describe something the customer did. Proposal sent is a seller action and can be achieved on a dead deal by a diligent salesperson. Proposal reviewed with the budget holder and a decision date agreed is a buyer action and cannot. Applying this single rule to an existing pipeline usually moves a noticeable share of deals backwards, which is uncomfortable and precisely the point.
Keep the number small
Four to six stages per sales motion is enough for most businesses. A stage earns its place by implying a different next action; stages that do not simply create disagreement about where a deal belongs, and that disagreement destroys the conversion data the stages were built to produce.
Separate pipelines for separate motions
A short self-serve motion and a long enterprise one have different steps and different buyer actions. Forcing them into one set of stages produces a pipeline where half the deals skip stages and the other half sit in stages that do not apply, and the reporting describes neither.
A worked stage design (illustrative)
Qualified: the buyer has confirmed a problem in their own words and agreed a next meeting. Discovery: the buyer has described how the process works today, what the problem costs, and who else is involved. Evaluation: the buyer has seen a demonstration tailored to what they described and confirmed it addresses their situation. Proposal: the proposal has been reviewed with the person controlling the budget and a decision date is agreed. Negotiation: commercial terms are being discussed and the approval and paperwork steps are mapped with dates. Five stages, each defined by something the customer did. Notice that a salesperson cannot advance a deal through any of them alone, which is the property that makes the pipeline worth reading.