Bevans6 ~ yes they have to be cut off. But when we used them on a new engine install with all new hoses it was a very slick looking installation and never had a leak for the time we had had it! ( I did have a plastic tote in a luggage bay with some spare old hoses & clamps of various sizes & utility knife just in case)
Clifford ~ Again looks like you've either done better research or had a better informant than I did. I do have the cut off tool somewhere in my tool box. (I think it was used once)
But I usually just take a utility knife and barely extend the blade out and kinda hold it more to the side than straight down and have cut off plenty of them and as far as I know never damaged the hose yet! (again as far as I know!)
Also I don't always use a heat gun, sometimes it is not practical due to space, lack of elec. power, or just that the smoke wrench or propane torch were closer. (yeah I know, I know they say not to do that!)
I have actually once used one without heating it at all on a service call on the side of the road when the propane torch had gotten bumped on while driving and was empty when I went to use it! (I tested it when loading up and it worked, 60 miles down the road and 2 hrs later when I needed it it was empty!) But these clamps work so well that once the engine starts producing heat they tighten them selves! (DO NOT try to use on a HOT engine &/or hoses or they will tighten up before you are ready!)
And yes I have used them on old hoses too. Can't reuse the clamp, but I have reused the hoses and used them on all types of hose not just the "blue" hose.
OK I ain't say'n I was supposed to do any of it the way I have, but I have done it that way and it has worked OK for me so far!