"Only sociopaths, engineers, and scientists use more than 4 digits of pi. Which one are you?"
(Obviously not exclusively; there are times for more precision)
Four digits is almost always more than you need, though. If you need more, you probably:
- failed to make something balanced
- missed an opportunity to have something be self-calibrating
- used open-loop instead of a feedback system
- didn't taper a hole
- are measuring the wrong thing
- ... or similar.
It is probably ok for estimating how many pavers you need around a circle garden bed.