It all depends on the actual numbers. If you are consistently getting 2’s, 4’s and 5’s then that means you have a large sample. Every statistic someone provides should come with confidence intervals to better represent the data. The worse the actual SD, the more likely you are to get bad results with a low sample size. Shoot 30 rounds with shitty 223 ammo and look at the data in the form of 3 shot samples, some of those might come back as super low SDs. Also people use SD to say load A is better then load B but with small samples and close values, the confidence that load A is actually better then load B is going to be super low. I personally wouldn’t be happy with a 30% confidence unless I was happy with either data set. There are tricks you can do to increase the sample size. Example would be treat 40.0, 40.2 and 40.4 as one sample and compare it to 40.6, 40.8 and 41 as the second sample. You will get worse SDs but you will have more confidence which part of the charge weight range has your best load.My Chrono data looks similar to what you posted above. Yet your SD wasn't 15 when you added it all together. I think what the take away here is that if you cherry pick strings of 5 or 10, yes, your true SD is probably significantly higher. But if you're consistently getting strings with 2's, 4's and 5's, it's probably not going to climb to 20 plus over 50rnds.