This is going from memory
if you program a chase without timing, it will get its timing from either audio or from the tap. If you just press tap once, then I think it goes to the max value of 10 minutes. You can then use the step button to manually trigger each step (or a footswitch). Also, if using tap, the speed slider will adjust the tempo for more percision. I find that about 0.3 seconds is good for most beats if it just a measure or two. I do know that all of this info applies to the Par Can side of this board. And I do know for sure that if you program a chase w/ its own fade times, if you choose audio it will follow that tempo instead of the one you programed.
Anything specific your trying to do?
--Kev