Gated reverb is used on snares to beef them up and give them a distinctive slamming noise; although it’s associated with Phil Collins ballads, it’s also used by breaks producers a lot.
Applying a phaser to high hats is a dnb trick; it makes them sound like lasers or running water if you get it right.
What these effects have to do with renoise is that these effects IMO sound best static, and they can be applied to samples with the “Apply FX to sample” button in the sample editor. This way, your snares will automatically “gate” their reverb when the sample is cut, and phaser hats can be perfected so that the phasing is perfectly in time with the hats (because the phaser effect has been destructively applied to the sample).
So…in order to avoid reverb complications and the cliche problems with having a phaser continually running, “Apply FX to Sample” is your friend…(don’t forget to destructively apply DC offset correction, normalisation, and compression in that order while you’re there).