The advice for leaving mags loaded to break in the springs has also been beaten to death, and is incorrect.
Springs weaken by full cycles, load, unload, load, unload.
You can leave a magazine loaded for 30 years, and that won't weaken, "season" or break in the spring one bit.
If you want to make your magazines easier to load, go out and use them.
Full cycles of compression and decompression.