I use mine for every new gun to get its baseline. Then while/after tuning it, recording all the different parameters of the tune options. After that only crono when a problem seems too arise, crono double checks there is a problem. Then use the crono after repair/tune to reestablish correct baseline tune.
Also use it when trying out new slugs/pellets to find their 'sweet spot'. Without a crono its hard to judge fps, which is the only way to find the optimum fps of a given projectile. Also find it useful to tune/record new barrel/pellet/slug combos fps at best accuracy/@ specific distance.
Imo, if you're just going to shoot the gun out of the box with no tuning other than the power wheel and pellet choices, then crono is nice to have for a baseline and to record pellet performance, but not a necessity. Once you start twisting that hammer spring tension, adjusting that regulator, changing fill pressures, porting valves/tp, etc, then a crono is essential. A tool that allows us not tune blindly...
So to answer your question, I can go months without using my crono, then use it every day for a week or more. Just another tool, like a wrench. My x wife called me anal retentive because of all the expensive equipment and tools in my shop. I really enjoy having the correct tool for the job, and find a great crono needed and cherished dearly...
jmo