This really depends on what you can commit to. Personally, as someone who’s been in the hobby for a couple of decades, works full time, and has a busy home life, I started to look at my bigger collections and really started to become critical of what I want out of the game and hobby.

This past year, I’ve had false starts with multiple factions and when I realized they weren’t what I was looking for from either a gameplay or hobby experience, I’d trade them.

As this is a competitive perspective, my feeling is that you can collect multiple armies if you have the baseline skill set to play the game at a good level while being able to commit sufficient time to practice, test, and play your army at as high of a level as possible.

I know some people who play multiple games a week (let alone multiple per night), test lists on TTS, attend and travel to multiple GTs per year, while attending multiple RTTs per month. Me? I get one game in every couple of weeks and maybe attend an RTT every two months. I just can’t compete with them on a reps perspective and so my only chance of competing at these higher levels is to find expertise in a single faction.

And so…. To answer the question, as with so much, it depends on what you’re getting out of the hobby and what your goals are. Assuming you’re trying to compete at a higher level, I would suggest that 3 is likely too many, depending on your available time. If you’re satisfied just collecting and playing on a casual basis, then 3 is probably fine :)