What do you typically see for the life of one of your bits?
Life span is determined by so many variables, is the end mill carbide, is it coated, what are you cutting, have you ever let the bit get to hot?
My oldest 1/4 inch carbide 2 flute downcut bit has maybe 20 hours of cutting in hardwood and it still cuts as well as it did on the first cut. I have no idea how much longer it will last, but I would guess at least another 100, who knows?
In this video about making guitar necks they say a cutting tool will make about 1,000 guitar necks before it needs replacing. Which is 10 full days of use. So I guess they are getting about 80 to 100 hours out of a good tool.
With carbide endmills or router bits of appropriate geometry, a LONG time. I did my entire 30-piece Massdrop run (120 2x2 squares cut out - entirely milled away, not a profile cut - of walnut to a depth of 1/4" in a single HSM pass) in walnut with a single 1/8" upshear Freud router bit, and it’s still cutting like now.