By that definition, it's a crap measure for angling proficiency.
If you went to a little freestone stream and caught 60 brook trout in 3 hours. You caught
1 fish for every 3 minutes.
I went to the Letort and caught 9 Letort browns in 3 hours.
I caught 1 fish every 20 minutes.
Who was more of a proficient angler?
Not a crap measure, just highly subjective. To truly measure this we would have to have the anglers fish the same creek at the same spot in similar conditions.
In your comparison I would actually say that although the numerical value of the guy fishing the freestone is higher, you are a more proficient angler as it is more difficult to pull off what you did. I consider myself a moderately talented angler and I could easily pull off 60 fish in a several hours, probably more than 3 hours though, on my preferred native brook trout creek. I'm terrified to even attempt the Letort and also don't live close enough to it to fish it on the regular. I'd probably get a fat goose egg if I fished it.
Again, difficulty of the watershed needs to be factored in too, though again, that is subjective.
At the end of the day I don't know if we can quantify an angler's skill into real tangible data. I guess an angler can say that they can produce a certain result on a certain body of water. If another individual can't match those results then they are inferior. But again that just means that that angler can't replicate those results on the specific stretch of water.
In this sport there are too many factors to go off of that can give one angler an advantage over another. These factors can consist of casting competency, knowledge of the water being fished, knowledge of fly selection and how to fish said flies (and where to put them), gear advantages (this one can be easily overcome by angling skill, but still a factor), stealth, knowledge of how to use a rod, line, and reel effectively, and most importantly, time spent in the hobby. What makes this hobby truly amazing is the near-F1 levels of trying to perfect everything from the angler themselves all the way to their flies. The learning curve never really stops.
So at the end of the day a fish catching cyclic rate simply states that an angler catches a certain amount of fish over a certain period of time.
I wouldn't even say I am that concerned with a fish cyclic rate as others may be, I fish because it's something to do and we are in the season where it is beneficial to fish for trout. My cyclic rate for this week is poor, 11 trout over 4 days and I probably fished 3 hours each day, so my cyclic rate for easy to catch stockers is almost a quarter as fast as sixfootfenwick's Letort run where the trout are much more wary . I only keep time when fishing alone. I keep it on my cell phone so I won't keep track of the time if it rains.