low stakes cash (10nl and below) yes. Don't play many mtt's tbf. I think a pretty large/substantial sample size is needed to determine one way or the other if you are profitable or not.
Being up some money after a couple thousand cash game
hands doesn't mean much. Just the same as being up after playing 100 mtt's and winning one, doesn't mean diddly squat. You could lose money in 99 of 100 of those mtt's, get lucky and sun run your way to a win in the 100th mtt, be up money, while still being a massive losing player.
In my opinion you need at least 100k cash game hands at your stake level to determine profitability
In my opinion you need at least 1000-1500 mtt's at a stake level ( $3.30 to $27 for example) to determine if you are profitable at that level.
In poker you can go on runs where you are hot as the sun, and over a small sample size be crushing the games you play. Then all the sudden like a light switch, you cannot win a hand, you are losing money every session you play ect.
At the end of this large sample, when it all shakes out, you can then determine with decent accuracy if you are a winning player or not.