Longevity of bucket of balls

[BevelDevil]

How long would a bucket of standard pressurized balls maintain their usability for drills, mostly groundstrokes? In my case, it would be a bucket of 36x4 per session, one shot each, 4 times per week. Skill level, say, intermediate recreational.

Also, would Penn/Gamma pressureless be a good substitute?

 

[Injured Again]

At our club, the junior lessons use pressurized balls stored in an open air hopper for a few weeks before they are rotated to ball machine duty. The pressure loss slows over time so they remain stable as a low bouncing ball for much of that time. But rubber also work-hardens as the ball is hit and after that initial few weeks, even if the pressure is retained the balls become slow and play differently.