In part it will depend on the type of rifle it is being fired in. Light loads in a bolt action rifle stress a case less than heavy loads, or service loads in a military type semi-auto rifle.
Experienced wisdom for use in a rifle like the US M-14 design, is no more than five total firings and scrap the case or relegate it to manual bolt action service. M-14's (and likely some other gas operated rifles) are notorious for jerking the heads off of cases when you try to get more than five shots per case. Some rifle and case combos may have trouble after 4 or even 3 firings.
One final word of caution: As a bottle-neck case flows forward and grows longer with each firing, its neck wall also typically grow thicker while the case wall near the cartridge head gets stretched thinner; which causes semi-auto head separations when fired too many times. You can easily trim the neck to adjust case length. However, increased neck wall thickness is another matter. Bottom line, if you are going to continue to shoot cases that you have to trim for length; measure the neck diameter of each loaded cartridge to insure that it does not exceed maximum blueprint dimension. Failure to do so can and has blown up rifles.
Be safe, not sorry.