I'm a recent starter to mulching and my experience is that it works best on dry regularly cut lawns in winter, spring, autumn in S E QLD - in summer, if it's long, wet and particularly if it's thick, forget it - I've just cut one - mix of couch/carpet grass - 2 1/2 weeks old - probably round 100+mm long and we've had showers in the last 24hrs - started out with the 217 set to mulch - OK for about half a dozen rows then you can hear the engine start to labour before it starts to spit out clumps of green paste - and when you stop the engine a couple of kilos of goo which has been held up by the updraft drops down (usually onto the driveway, staining it green) - I used it on one patch then went and got my full chute pushie with the flap tied up to finish the job.
Direction of debris throwout and major buildup in the under deck - is almost always to the right hand/starboard side of the deck.
If you are catching make your passes with the uncut grass on the right hand side (picks up spills on the next pass).
If mulching or throwing keep the uncut grass on the left hand side (so you are not running over the windrow).
EDIT: If no catcher, make the first pass or 2 so it throws the debris away from paths, fences, buildings, then run the rest of the passes so the waste ends where it makes your life easier.