Quote Originally Posted by rpjazzguitar
The musicians always know where they are in the two bar clave. But, after a long stretch it's possible to lose track of which two bars you're in, within the four bar repeat. And, it happens even to decent musicians. Maybe it shouldn't happen but there can be distractions on a bandstand.

If the leader cues reliably exactly 4 bars ahead of the transition then it's pretty easy. Two claves and go. But, in my experience, some leaders think anywhere in the last four bars is just as good. In that situation it might be two claves or it might be one or even just a half bar, I suppose (although I don't see that one). Their idea is that all the players know where they are in the 4 bar repeat so a cue anywhere in those 4 bars means to transition after the 4th bar.
fwiw I agree that the cue should be able to come anywhere within the 4 bar vamp (regardless of whether or not that 4 bar vamp consists of a 2 bar clave played 2X). But I also believe it's the leader's responsibility to give the cue fairly close to the beginning of that 4 bar vamp. Doesn't have to be precisely on the downbeat, but it should definitely be within the range of "this time through is the last time through!". So ideally within the first measure of the vamp, just to be safe.

"Half a bar" from the transition? Not if you're conducting jazz musicians.