Hi @EPiCRob,
There isn’t any report that I know of that lets you explore this information interactively (with dropdowns, freely adjusting the number of days etc).
You can however create a custom deal report (Menu > Reports > Reports > Create custom report > Single object > Deals) and set the filter of that report so that only deals with a certain time in a stage will be displayed. If you want a way to see which deals are currently too slow, that’s how you’d find them:
The time in a deal stage is measured in milliseconds (why tho), hence the 432 million.
Let me know if you need further assistance with creating this report.
(By the way, under Menu > Analytics Tools > Sales Analytics > Sales Outcomes > Deal velocity you’ll find a report that doesn’t answer the exact same question but is driving home a similar point.)
Best regards!