Your thoughts and experiences mirror mine. Why would you make a range trip, a comp. a hunting trip etc.. to have your rifle come apart on you? I've read too many, my rifle is a 1/4 moa gun, I wait till it opens up to half moa before I clean. I imagine all testing is done at 100 yards so if your groups opened up to 1/2" at 100, I bet they look sweet downrange.
Once a barrel is broke in, you have a load, after 150-200 rds, just clean and shoot while monitoring the barrel to determine how long it can go one time is easy. It becomes the baseline, even though most barrels get better as they have more rds down them.
With todays cleaning solvents, cleaning rifle barrels is a breeze, it's no longer waiting on worthless hoppes #9 and wearing a mask with sweets.
Plus there are quite a few indicators that things are about to go sideways. Your load seems to be shooting low for some reason, the muzzle end of the barrel may be fouling bad, creating drag. Your load seems faster but still hammering, maybe your powder is laying down some extremely hard carbon just past the throat area. Either way, you are about to do some cleaning.
For the price for one the Teslong borescopes compared to what we stick into this hobby, it is borderline foolish not to own one. Less money than a box of 230gr Berger's, or any box of atips.
I hear this all the time, Wait to clean when it starts shooting bad. I do what you recommend at the beginning of barrel life cycle. I break the barrel in, work up a accurate load for hunting/shooting, once the load has been found I test the accurate number of rounds it can shoot before I see a decline in accuracy. This tells me how often I have to clean. Normally it is less than 10 rounds.
The reason I like this method is because the rifle is always shooting it's best even if I'm not. I have confidence that if I spend a lot of time and trouble getting to the point of making a shot, it will perform at it's best and a good Point of impact is achieved. (Every Time).
I don't want to go to all the trouble of planing and executing a good hunt, only to have a fouled barrel to spoil the hunt with a poor hit or a miss.
Why wait for poor accuracy to show up?
J E CUSTOM