I am a six stringer but counting measures usually only happens when we first rough out a piece. As soon as we know it pretty well everybody just feels the groove and each player has a cue to go to the next section. Sometimes it is a riff, chord change, 1 measure snare accent etc. Get in the groove and follow the cues. Our drummer has a jazz/prog background and if we are doing a 4/4 and he thinks you are sleeping, he might just throw out a 5/4 measure to see if you wake up.
He keeps us on our toes and listening to each other.