Unfortunately this is a fundamental misunderstanding of how things work. Both the physical and the mathematical aspects.
There are no such things as velocity flat spots or "nodes" when we are talking chronograph numbers. I'm not talking about POI on paper at various distances.....that's an entirely different topic. It's basically impossible to go from 77.1-77.4 and only have a few FPS difference. What you're seeing in small sample size "ladder" tests is random dispersion through the ES of a powder charge that happens to overlap.
I.E. 77.1 was on the high end of the ES and 77.4 was on the low end of ES. So they give the illusion there was a "flat spot" or "node." As you can see when you ran it again and got a velocity dispersion that is more realistic. This time, your sample size didn't overlap. I think you can see where I'm going with that.
The other misunderstanding is with ES and SD. If you have an SD of 2.3, you will have an ES of over 10fps 95% of the time. So that 4es really means nothing. And you wouldn't have listed it if you understood that (I'm assuming, I apologize if incorrect). Also, you'd need to extrapolate that 2.3 SD with the amount of shots fired in the sample size and a 95% confidence interval. Which would then give you a realistic range (you'll never know your true SD (and by default, also your true ES) without many, many rounds fired. So, we need to extrapolate the sample SD to a realistic range. That allows us to objectively compare different load data and determine which are noticeably better or worse than the others. And then which ones are likely around the same as others.
The TLDR: no, don't do another velocity ladder. It's a waste of components/time with no objective reality.
With that low of an SD, even if just 5rnds, it's very likely that your true SD is under 7fps, which is a very good place to be. If it was only 3rnds, then you're very likely to be under 15fps, with something like a 66% chance that you're under 10fps. Regardless, 2.3fps even in a small sample is indicative of a likely good load.