Two reasons I soak my feed pellets for pole or waggler. The first is that dry they can sit in the surface tension and not sink immediately. This means they can drift out of the area I think I am feeding.
Second is that when soaked they swell up. This may seem a small point but I would rather they swell before being eaten by the fish. My theory being that if a fish fills up on dry pellets that then swell inside them A) it could cause damage B) it may mean it takes longer for the fish to want to feed again.
Halfway house is to wet the pellets enough to break up the smooth surface so they sink and don't float but not left long enough in water to make them swell. That way they may fire more accurately from the catapult. A 30-60 second soak should be enough to do this with most pellets.
Never on the PW having them float for a second or so can help get them competing shallow.
Feed, Cast, Feed,Twitch.
Repeat the process dont leave your bait stationary more then 60 secs.
The harder you work on the PW the more you will catch!
If you mean pellet waggler, then no need. To add to what endpeg said, it is worth varying things sometimes. Somedays they will take on the drop immediately after the cast, others they will take on the twitch, somedays they will take whilst the bait is suspended and you have fed over the top. Feeding around whatever strategy works on the day is best.