Pixie cut maintenance

I initially got a pixie cut in May. After letting it grow out a bit, last week I went in for a trim, as my stylist offers free bang/trims in between full haircuts. I was kind of shocked to discover how long it was, even after the trim; I did not realize my hair had grown so quickly. I now think I may need to go back in for a full haircut to get it back to my desired length, but I'm a little hesitant given that my stylist is pricey (she's worth it, but it's not a small investment).

For those of you with pixie cuts, how often do you get it trimmed? How often to you get full haircuts?