You want to do well in crits? Train like a crit rider. You want to train like a crit rider? Listen to ole rkwaki as he is too stupid to road race...
I believe that crit training is very focused and more 'painful' as intervals suck, gym work sucks, finding that aggressive streak can be difficult, getting the balls to stuff yourself through a 45 cm opening when you have 42 cm bars at 30+ miles an hour can be very difficult as sometimes what you think you want and what you really want have a big disconnect between them.