Some firearm instructors & tactics trainers advise gun owners to leave a round or two off to reduce the tension on the pistol magazine spring. This, to me, isn't bad advice, but most modern firearms & metal components are engineered to last for long periods.
By the nature of spring mechanics, springs are only worn out from repeated tensioning and loss of that tension, not from just the application of tension over a period of time. Same argument comes up whenever people balk about leaving guns with the slide locked back.
The idea that leaving mags loaded or guns locked back has any effect on the spring is akin to believing that leaving a car on the ground for an extended period of time without moving will eventually wear out the coil/leaf springs. If this were true, we would all need a lift in our driveways for when we went to sleep.
Surprising how much installing rich kids coilovers can teach you about unrelated things.
I got a Ruger P95 in October, bought 6 extra mags the same day, have had all six of them loaded since the day I got them (MECGAR mags) and I just checked one, spring is near as stiff as the day I got it. The two that have softened are the two mags that came with the gun, which have seen probably 1200 rounds each.
However, if you are talking about the tension that interferes with feeding, this is typical of mags that have not been completely broken in. A properly broken in mag (the two that feel the softest of my 8) feeds much more reliably than a stiff, new one, regardless of whether one of them is full or not.
It won't shoot if it isn't loaded.
All I will say to that - famous last words. Saw a buddy lose a piece of his kitchen floor, and a washing machine in the basement off of that idea. Nothing crazy, but an M4 blast in a tiny kitchen and a visit to the audiologist later, "not loaded" doesn't exist to me.