It certainly is a "preference thingy", but for Pete's sake, how long does it take the gear to cycle? We're only talking a few seconds here.
One of my personal pet peeves is doing things the way they used to do it "way back when" just because that was the way my old gray haired instructor taught me. A case in point...
A few years ago I was giving a guy a combination BFR and instrument competency check in his light twin. When he did the runup he cycled the props at least 3 or 4 times. When I asked him why so many times he told me that that was the way he had been taught. When we got back to the office I showed him in the flight manual where it was only necessary to do it once - to check the prop governor then continue on into feather. It turned out that his instructor had flown B-24's during WWII. It was necessary to do that on those big radials to flush the cold oil out of the propellor hubs. The problem was, the old instructor had never bothered to read the manual on the new Continentals. Old habits die hard. It's not that it's a big deal, you probably won't hurt anything doing things that way, but all it shows is that you haven't read or paid attention to what is written in the POH.
This thing about hanging on to the throttles for "dear life" is not a bad thing, but again a lot of it comes from the old radial days - some of those big engines had a propensity to backfire back through the carborator. When that happened it would slam the butterfly shut and take the throttle along for the ride. Also, those big engines were known for their vibrating - which also had a tendency to walk the throttles back. With today's engines, it's not that big a deal. In fact with turbine engines the drill is to remove your hands from the throttles once you have achieved V1 - it's too much of a temptation to retard them if something untowards were to happen above that speed.
Back to where you put your hands...
In my humble opinion, it's a very good idea to keep your hands on the throttle(s) when you're on approach and throughout the landing and of course, throughout the initial part of the takeoff. But remember, that there are times when it makes sense to have that hand doing other things too.