I spaced out my broccoli a little more this year. In previous years I have planted them about 12" apart in order to acheive a "broccoli hedge" (I like hedges don't I?). This year I had more space and fewer plants.
EVERY day I have to search the inner and outer leaves for caterpillars, and every day I find more than one. The colder nights in the last week might help keep the numbers down. Carry on squishing!