It depends on how many games I play. If it is just a game or a 3 game tournament i will usually make 1 to 2 mistakes (per game). But if it's more than 3 it starts to snowball.
In the past I have tried to mitigate errors by running less demanding lists. I think that might compound my mistakes because I am not as familiar with those ships so this year I'm going to see if I'm better off running a more demanding list.