does the midday hit rate actually survive position sizing?

Read the research piece arguing the open isn't the only tradable window, and I've been chewing on it for a couple of days now because I think it's making a subtler point than most people will take from it. The headline everyone will grab is "you can trade all day." Fine. But the number that interested me was the share of minutes where the available move covers the round trip. In the open that share is comfortably over half, and in the dead part of the day it drops to something like a third-ish. What I keep turning over is that a hit rate isn't an edge on its own, it's one input. So here's my actual question. If the frequency of cost-clearing minutes falls but the *size* of the clearing moves doesn't fall proportionally, then midday might just be a lower-frequency version of the same game and you size accordingly. But if both fall together, you're in a genuinely worse regime and no amount of sizing discipline saves you, you just lose slower. The piece reports the median ratio and the clearing share, which tells me about the middle of the distribution, but not much about the right tail. And for anyone using a fixed fractional sizing rule, the tail is where the whole result lives. Second thing that bugs me: the ratio is computed against the round-trip spread, but my realised cost is spread plus whatever slippage I eat plus the fact that I don't get the best exit in the next ten minutes, I get the exit I actually take. Call it a haircut on the haircut. If the median midday minute only barely clears cost in the idealised version, a realistic execution assumption pushes a big chunk of those minutes underwater. Which makes me suspect the honest conclusion is narrower than "opportunity exists all day." It's more like "opportunity exists all day for people whose execution is close to the theoretical best exit, and gets thinner fast for everyone else." Anyone actually tracked their own fill quality by time of day? I've got a spreadsheet going but only a handful of weeks and I don't trust it yet.