What this is worth to you
Put in what a case study costs you today. The arithmetic below is yours, not a claim of ours.
What it costs you now
A win-rate change you want to price
Why we will not quote you a return
Plenty of tools will tell you that case studies lift close rates by some confident-sounding percentage. We do not know your win rate, your market or your proposals, so any number we printed here would be decoration. The only figure we can stand behind is the one you can check yourself: the hours a case study costs you today, against the time it takes to read and approve a draft.
That is also why the win-rate row above starts empty. If you want to price a change, enter the change you think is plausible and the page will cost it out. The assumption stays yours.
How often this is worth doing
Once per finished project
At handover, while the numbers are still at hand and the client still replies quickly. This is when evidence is cheapest to collect and approval is easiest to get.
Before a pitch you care about
Pull the two or three past projects closest to the work on the table, and take the drafts into the room with their sources attached.
When a claim on your site has aged
Re-run the source. If the supporting sentence no longer holds, the statement will not survive, which is the point.