Glock magazines are a bit of a pain to disassemble to inspect. In my last armorer recert they told us that Glock was now recommending not to disassemble magazines frequently, so the plastic parts holding them together wouldn't wear as quickly.
When it comes to all the other magazines I use, I like to dissemble and inspect them, looking for components issues, to confirm proper orientation of springs & followers, etc. I no longer do that with NIB Glock magazines. I just check for normal follower movement and spring tension (loading and unloading the magazines).
I prefer to function-test new magazines that I'm going to put in a carry rotation by firing at least 25rds from each of them, and up to 50rds each if I have the time and ammo available. Those numbers were decided upon because for a while I was pulling rounds from new boxes, and they were 25 & 50rd boxes.

However, when I was pulling rounds from a bin of loose range ammo, I was usually satisfied by fired 2-5 full magazine loads from each magazine ...
and I was running the mags for regular quals and practice drills, so sometimes more rounds might end up being used in any particular new mag.
Bottom line, I want to walk away from the range having complete confidence that the magazine will be reliable if I have to immediately use it for self defense.