Cycle testing takes a long time and ties up a good charger for the duration. In the radio control world there are folks who do it but they are lucky in some respects as current draw from the typical RC device (am thinking electric aircraft) is quite high so the discharge cycle is relatively short in duration. Li-po packs can also be charged at quite high rates many times "C".
If you were to do a cycle test at the various light discharge rates commonly found (not those relative few extreme output light users) in our lights ( some < 1A, some at 1A, some at 1.5A, some at 3A) and at the charge rates most use (frequently well under 1A) to simulate average use, performing hundreds of cycles would take many hundreds of hours per cell.
Anecdotally it does appear the better cells deliver better performance over more cycles.
Unless you need to buy hundreds of cells for hundreds of lights and thus have a meaningful budget to apply to cell purchases, why obsess over this anyway? Buy known good cells and be happy. The price delta between really good and questionable is not so large as to prevent anyone buying a flashlight from enjoying both peace of mind and an expectation of long cell cycle life.
Also It would be great to test how charge/discharge voltages affect battery-life (charging to 4,2V vs 4,1V, discharge to 3,0V vs 2,5V etc...storing half-discharged or fully charged...)
The U.S. Army has done this; somewhere back in my posting history - might have been lost in the great crash, dunno, can't remember if my thread recovery tool recovered that thread - I started a thread that posted their results and IIRC the ensuing discussion was interesting. Unless the best applicable knowledge has changed since then the bottom line for me was the best cell cycle life could be obtained by avoiding charging fully. I don't believe it is known whether faster aging is a result of merely hitting max charge voltage (nearer 4.2V) or whether it is a factor of how long the cell stays there. I speculate that aging accelerates by hitting 4.2V or thereabouts given the U.S. Army cycle tests would not have left the cells in that state for an appreciable amount of time.
I'll find that thread and post some discharge tests of cells I've been using actively over the past two years. My bet with myself is that they still perform quite like new, as they still come up to the same voltages I recorded when they were fresh out of the box, as measured coming off the Pila, +/- a hundredth of a volt. None are suffering significant sag after sitting 24 hours post charge.
If you really want to obsess over this (I have been guilty of this at times myself) you could mark some cells and treat A as "normal", always charging fully, and B, C, D... as a low charge voltage specimens - purchase a hobby charger that is able to adjust the CC/CV parameters to complete at 4.0 or 4.1V. If the somewhat reduced runtime isn't an issue for you, maybe in three or five years you'll discover a pattern. Whatever you notice might not stand up to scrutiny given the small sample size but it may be interesting nonetheless.
Or you could just buy good cells and enjoy the light they help deliver.
For a while I was tracking every charge but gave up on that. As a result of the thread mentioned I did decide to change my charger's termination voltage to 4.1V for cells in regular use. Spares I don't intend to use for awhile I leave sitting at a lower storage voltage. If my PL8 is busy and I need to recharge some cells I don't sweat it and pop them on the Pila charger and let it terminate normally. Has more careful than usual treatment helped extend their cycle life? I've no idea.