yeah- I read that somewhere- (probably here) that you never max-out your clip. It may hold 30 but you only put 25 in there (or 28) to keep from stressing the spring to the max.
I am NOT an expert at all- I just like guns
The physics on springs -
if you do not stretch or compress a spring past its point of “plastic deformation”, it will ALWAYS return to its original shape.
You don’t have to worry about overloading any magazine of decent quality.
You don’t have to worry about unloading your mags to save the springs.
The springs will not compress and “stay there”, ie, not load the last few rounds in the mag.