Probably true.
To my inexpert mind, it could be that a slightly ragged edge from the coarser stone feels sharper. I guess it depends on how the OP is measuring the sharpness. I do know a bit about Sharpness, but that's hardly the same thing.
Interestingly, if you're testing knives, a knife slicing with a coarser edge will last longer in many of the tests, but it doesn't last as long with chisels or plane irons (or enter a cut as easily - we're kind of pushing things into a cut and most knife tests slice).
I found this (longer coarse edge) kind of shocking, but I guess it shouldn't be and it does a good job explaining why sharpening something and examining duration or failure doesn't mean sharpening something else with different use, steel, hardness, geometry will yield the same.
I'll leave sharpening carbide to the machinists.
A very good simple test of sharpness for planes is to take three irons of the same type, set them up with a 25 degree grind, a 33 degree microbevel and then plane the same edge of wood with them until each is dull, rotating each every 200 feet or so. I've done this several times and learned things I didn't expect to learn (at 33 degrees, most chipping stops except in very poor quality irons - at 30 degrees, there is chipping and no gain in longevity, usually - depends on the wood).
When you do a test of this type once you have a good sense of feel with steels, you suddenly notice effort differences and if it takes an hour to do this some lazy saturday afternoon, if you stick around and do any significant amount of hand work, it'll pay dividends indefinitely. You can gain back the effort improvement in a couple of sessions.
What I found is this (though others have found the same)
* stopping failure is necessary to get significant longevity - this always occurs somewhere between 30 and 35 degrees in chisels and plane irons (except perhaps for narrow mortise chisels)
* in plane irons, I started with 5 micron diamonds, then worked through various stones and ended with 1 micron diamonds. 5 micron diamonds planed 65% of the length of 1 micron diamonds, fine oilstones (both a fine washita and a black ark stone - the former is easier to finish an edge with and functionally similar in sharpness if it's not scuffed) go about 80-85% as long. Apparently, there is some duration gained above 1 micron, but I don't care - sharpening is more than two steps at that point and I'm out. The 1 micron finish only has to be at the very very tip of the tool and can be applied after a medium stone
I didn't go coarser than 5 micron diamonds, but they were loose fresh diamonds, and that's a very brash edge (like a 1500 diamond plate that's worn in). if you don't mind diamonds (autosol is fine if you do), the tip polishing replaces a strop and you're still sharpening a plane iron for about a minute and less for chisels. If you do the job right, you'll be sharpening wear and not edge damage.
I've run these tests, others have, etc (I mostly ran my long test to check how well irons live up to their claims of planing duration - most do reasonably well, except blue steel japanese irons match O1 at higher hardness, and A2 doesn't really gain much for its abrasion resistance as the duration over O1 (25%) is with a horrible edge condition, and it hates some natural stones).
The trick after testing these things one on top of another is figuring out how to do them without spending extra time or without much. That didn't turn out to be that difficult, but not separating setting up geometry and then just polishing the very tip of the tool creates the illusion that they will take a long time. One minute per plane iron for all of them - drastically reduced effort planing, drastically higher chance of finishing an edge, and no guide needed.
The results were not what I expected, but results are results. Knife slicing tests give us a good indicator of a steel's ability for longevity in wood as long as the steel is fine enough and has enough toughness and hardening potential, but slicing tests and edge coarseness don't match.
(I still don't use diamonds, but the results were consistent and stark - and squash some OWTs about natural stones creating longer lasting or sharper edges. They don't. It's OK that they don't - but difficult for some people - generally not on this forum - to admit that they prefer something that doesn't work better. Everyone wants their choice to be the best).
