What types of knife steels do you need to strop ?
Look into diamond and/or CBN compounds or sprays.Not so much for 12C27 and 154CM steel, but especially on S30V (and anything with more than trace amounts of vanadium carbides in it) diamond and/or CBN will give you way better results than even the best green compounds.Your edges will become sharper as well as stay sharper longer.Cheapest would probably be the Chinese diamond pastes from E-Bay, but if you spend a bit more money you will get better grading as well as a higher carat weight elsewhere.
I've used some of the diamond sprays and pastes. I prefer the spray. And they work well. But I also use a green and a pink stropping compound. I use a light rubbing on the strop. No need to put a thick layer on. For the straight razor I shave with, I start with green, then pink, then ~1micron diamond, then smooth leather. Seems to work. I don't refresh the diamond strop very often. (In fact, I'm not sure where my bottle of diamond spray is...... )
Tough question to answer accurately. It would depend on a number of factors, e.g. strop, use, steels, etc.... I'd say it lasts well. The strop material gets impregnated with the small diamond particles and works well for a long time for me. Now, I'm using the strop to restore the edge, take out micro-rolls, and remove burrs. So, I'm not looking for a lot of 'cutting' per se. It's more a polish of an already honed edge. I can only say that it's worth trying and seeing if it works for you.