I shoot my handguns at an indoor range primarily - so I pick up some of my brass and a lot of stray stuff. Is there a limit to how many times - yes, but if it isn't a hot load I would not be afraid to load even a 9mm case 8-10 times. A heavy case like a .45ACP can be loaded a lot longer than that - maybe 30 or more times.
Honestly I don't really fuss with how many times I've loaded a case - but I do run every finished round thru a "case gague" before I box them up. If there is any dent or deformed spot on the case that was not removed by resizing, or if there is a real fine crack - then that round will probably not drop in and out cleanly in a case gague. Any round that doesn't drop in and out cleanly - I pull the bullet, reclaim the powder, and scrap the case. When I sort cases - prior to cleaning - if something looks beat up I just dump it. After I clean them - if a few of them are still black - I dump them.
Loose primers - I have not had a problem with any - in any caliber. Unless a primer fell out of a finished case I don't know how you'd know it wasn't in there tight. As I box my reloads - I also label them - date, powder, bullet weight, etc - so if I do have a problem with some rounds in a couple of boxes, I can identify when I made up those boxes and make a decision about pulling some bullets and doing some testing or dump the whole lot (pull the bullets on the lot ).
We get a lot of cops shooting at my range - and a lot of ammo run thru Glocks - and with Glocks not having a fully supported chamber ( round near the bottom is not supported ) I do get some rounds that even though they are resized, there is a little bulge near the bottom of the case, that's a Glock mark, and it won't pass thru the case gague, I pull the bullet. So, yes, in my opinion, most Glocks will shorten the case life - or any gun that does not have a fully supported chamber.