[quote name='Dad3353' timestamp='1378404713' post='2199886']
Music doesn't have to be metronomic. Depends on style, certainly, but a variance in tempo can be very refreshing (as long as all are playing together...). So it varies slightly, or accelerates in the 'stronger' parts. So..? If it sounds good, go with it.
([i]This should not, of course, be a substitute for incompetence[/i]...)
[/quote]
Wholly agree with this.
It does rather put the onus on listening to what's going on around you and responding appropriately. It works best when everyone is able to 'respond in the moment' and adjust as you all go along together. If that can't happen, it may be best to have a referral source for the beat, which could be a bass, vocalist, or in other realms, a conductor etc