How many rounds to a magazine?

I was taught to never fill a 1911 .45 magazine with more than 5 rounds. Because to put the capacity of 7 rounds in a magazine would damage the springs and tension devices, overtime.

If this is true. And I see the logic. How many rounds should I put into my Buckmark magazine? 10 round capacity. I currently have 5 mags with 5 rounds in each. 7 may be more appropriate.

TIA!