Depends. Sometimes constant isn't possible. Sometimes it's too noisy for fish. Sometimes it doesn't matter at all. Yesterday, with 15-25mph winds, it didn't matter. I found a ton of bass on Joe pool yesterday that were feeding on shad that had kinda "blown" into a cove. Eventually I would be right on top of the bait balls and wouldn't catch anything. But, as soon as I'd get off the top of them, it was lights out again. I was in 3-4ft of water. So when I say on top...I mean probably scaring the hell out of them. Lol. Caught about 200 bass in a few hours. Honestly, it was almost 8 bass to 10'casts. Not one every cast....but close. It was the first time I have seen 4-5 largemouths fighting over a bait. I had what looked to be an "over 21" eat an under that ate my trap....lost them both. Haha. Had a 6" bass hit the trap and had a 3" shad in its mouth already.
Ok....back to the trolller.....
I think on the very calm days where bass are holding tight to cover(nervous) and in shallow water, it's probably best to be on constant low or off. Also.....shut off the pinging and clicking graphs. The biggest ones can associate those pings, clicks, and "wirrring" noises as trouble.