When I bought the SB1028F knee mill I bought a modest set of end mill holders and a fairly decent set of fractional inch size R8 collets all dedicated to that machine. (I have another machine that will use R8, but its still in the crate.)
Even with that modestly large knee mill I run out of z-height clearance unless I want to hang a part off the side of the table (which I do when its the only way). In order to maximize the height before I have to do that I have made some cylindrical spring collets for non fractional common drills like #7. This allows my to only subtract from available clearance by the amount the drill sticks out of the column.
I made most of those collets with a 1/2 inch OD. A few are 3/4 OD. Those are two of my most used R8 collet sizes, but I also use those shop made cylindrical collets fairly often. Tools I use a lot get left out on the bench. Often in the collet or tool holder they were last used used in. This means I have to take a few extra seconds to move the drill and cylindrical collet every time I need to use that size for something else. It only takes a few seconds to do that, but it takes a few seconds more to mentally shift from "the job I am doing" to "oh, I need to decide where to put that." Its probably inconsequential, and I probably won't ever do anything about it, but if I had made the outside OD of those cylindrical collets the in between 32nd sizes I never use, I could just leave them in the collets where they get used. Its not like I ever use those R8 collets for anything else... because I don't.
Make your cylindrical convenience collets in a less common OD size like
17/32 or 25/32 or any main collet or tool holder size you rarely or never use.