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.
this is true but springs get old and ‘loose’ - look at an old car that sags on coil or leaf springs
I have had magazines that were not springy at all- but i assume they were not that way when sold