I've heard that you can stream an analog drum machine into the session, and as long as the BPM is the same (say 120BPM), it doesn't matter about the interval and/or start time (i.e. it doesn't need to fire with a MIDI Start message), because that is not factored into how the synchronization of the streams happens on the back end.
There's this from the Wiki:
"Each client's data is synchronised against a distributed clock. This clocking is then used to distribute the data out to all the other clients so that they can play all the remote streams in sync."
But it doesn't seem to mention interval as being used for the calculations at all; kind of figured it would splice/stitch the streams at set intervals.
Ok and from reading those two posts, intervals are important from a strictly time-keeping/sync perspective, and that streaming an unsynchronized drum machine into the room with an arbitrary start point shouldn't work, because how would the server "know" where the 1 is?