Higher grit is not the issue, especially with belts ranging up to 3000 grit.
I did a demonstration for my boy scouts with a belt sander. I took a knife, and sawed concrete until it was dull. No edge at all, and hit both sides of the edge with a single grit (240 grit, if I remember) no progression, just worked up a quick small burr along the entire edge, then hit the edge on a chromium oxide loaded strop quickly enough to get the burr off, and shaved a big patch down my leg.
I'd you are getting a good apex, and removing the burr properly, you should be able to get pretty scary edges, hair jumping sharp with minimal grit progressions. If your fundamentals are solid.
Pay special attention on pressure and angles.
With a really fast moving belt, like those grinders have, you should not be having to use much if any pressure. You arn't grinding a main bevel, pre heat treat. Not trying to remove a lot of steel. The speed those belts run at, light pressure, quick strokes, mind the tip, don't round it.
Sounds like you have plenty of equipment to work with, especially with the higher grits, and paper wheels.
I can get hair whittling from a single grit stone (like a cheap Smith diamond stone and straight to a loaded strop.
Ditto for a few sheets of automotive sandpaper to strop.
Or diamond stone to a fine ceramic stick.
It helps me to have decent light, and pay attention to angles. Make sure you are getting the apex on each side.
With a strop, concentrate on your angle, and using no pressure/minimum pressure. Pay attention to the finishing of the strop strokes. Make sure you are not increasing past the apex angle and "sweeping" the edge. ( on a strop, the angle of attack is basically the angle at which the edge just starts to grab the strop to cut if you gently try this edge forward.... you don't actually need to cut the strop....i saw one idiot "expert" cutting his strop all to hell showing this) one. Many people also use enough pressure that the leather wraps the edge and dulls it. It is easy to polish an edge to mirror, but have a dull edge because you used too much pressure, or roll the spine upward at the end of the stroke.
Sandpaper sheets taped to a glass pane helped me get better at my mechanics on stropping. It is easy to see the scratch pattern as you switch grits. The glass is not forgiving of off angles either.
I have convexed many edges on a dense rubber strike pad on automotive sand paper as well.
Now, I rarely use my belt sander on my knives (fast belts tend to remove more material than needed). I still use it when I have a lot of material to hog off to get a desired result.
Mostly I set my angle with a diamond stone (I have a course and a fine). Then I hit both the standard Spyderco ceramic grits. These days, I often skip the loaded strop (depends on the steel and use).
A nicely apexed edge, off the normal fine Spyderco rod has a good bite, and will easily jump hairs off the arm (where the hair catches and leaps off either direction on the edge).
You can get polished edges that will shave effortlessly, but not cut some materials too well. I have backed off my tendency to over polish my edges, or spend too much time on the strop.
If I have a well apexed edge sometimes I will go from the fine diamond stone and do a pass or two per side on a strop, or even skip the strop and do a few strokes per side on a ceramic rod (usually held in my hands, because I can feel/get feedback from the steel/edge better).
There is no wrong or right. Technique is vastly more important than nice equipment.
Repeatability is also more important than even a perfect edge angle. Spend 1000 on a top of the line fixed sharpening system, with all the grits up to silly high numbers, and if you don't make a proper apex at the start, and move on to higher grits before the lower grits are biting, scary sharp, and you are just polishing a shoulder . Not the edge/apex. I've made that mistake with a fixed angle system. Also with hand held stones, and bench stones. And ceramic sticks. Etc.
Even off a 150 grit course stone, if you do low pressure, consistent passes, you should have a grabby sharp edge. Same with 400 grit "fine" diamond.
Many makers/manufacturers sharpen with a 400 grit belt then knock the bur off and it should jump hairs.
Even an uneven bevel can be sharp. I've done chisel grind, or other odd grinds and had wicked sharp edges. Even did a 1/2 convex (with one edge being convexed, the other flat, very low angle like some earlier Busse used to use. Worked fine. Strop the convex edge, edge trailing stroke on the flat side with a ceramic.
