When i started playing poker i was pretty much always playing mtt's, as do a lot of people when they start out i imagine, since feb i've been focusing on 100% cash games but on the side, when i have the time, i still like playing mtt's, for the "big payday" factor i think.
I prefer though to stick to a 1% rule for the mtt's i play, it's really nitty i think as i'm playing $3 mtt's with a $375 bankroll but with my main focus still being on cash games i don't want to risk too much of it playing in mtt's, something i'm nowhere near as skilled at compared to cash. Still though, theres plenty of 3k,5k guaranteed tournies on stars in this price bracket so it keeps me happy
Varying your game only takes a toll when your not practicing good brm across the board, for example, i play 4-10 tables of 10nl cash games at the moment but that doesn't mean i can go buy in to the sunday 250k for $11 just b/c thats close to what i'd buyin for at a cash table, the variance in mtt's, as you probably know, is huuuuuuggggeeee, so just keep a sensible head and you should be fine.
I play in the 3k guaranteed 6max @ stars for $2.20 whenever i have a spare 5hrs at night, first place for that is nearly 1k most of the time so you can still have a big payday one day and stick to good brm rules