well, there is competition, and there is the course. The max number of reloads you need to do in a course is 2 (when walking between 3 positions), and that's not timed. you only need to worry about a single timed mag change... So, in theory, if you pulled 2 mags from your back pockets to load at the start of each exercise, you COULD manage the course with 2 mags, if finances are tight. But it will make it easier for you to have lots of room for mags on your belt, so if you can, get up to 3 more (I'm assuming you're talking about single pouches, competition style). 5 will serve you well in competition (I've seen people with 4 and people with 6+, but 5 seems to be the standard average).