well there's an old addage that says "alls fair in love & war"...
captain hardegen was one of the most the most successful hunters during operation paukenschlag. he bagged something like 18 ships sunk, in two patrols no less.
u -123 would lay off the coast of the eastern sea board, watch merchants shove off, wait for them to get just deep enough to sink them!
now, if that's not cheating, idk what is.
cheating is having hydrophones that can detect contacts @ full speed when surfaced, ala vanilla sh5. what the hecks the point of radar at that point?
the coastal waters leg of total Germany warns of mines. I guess that's something to consider. whether or not they're out there I have yet to find out.
patrolling ... the buttons for search patterns in sh4 were convenient, in retrospect. aces of the deep did teach me to make my own nonetheless. either a rectangle that collapses on itself in legs to the center, I always liked the "hourglass" shaped pattern.
I think the trick is to not make the legs too big where something could slip through, like say a 60 ship convoy for example. at least once a leg dip down to listen for contacts, again this isn't "sound" strategy in vanilla sh5, as the need for submerged listening is moot.
when all else fails no, its quite alright to sit there & wait, although in real life the ocean currents would've had their way with you. its a lot less diesel that's for sure.
uboats were essentially surface vessels that had the ability to dive when needed, its in their very nature to be sneaky, or cheat if you will, so cheat away!