The chrono just helps for the really OCD types.
1. Let's you figure out energy (more useful for hunting rounds).
2. Gives you an idea of fps spread on different loads or within groups at the same powder load. If all your rounds are at the same Ogive OAL and you've separated by bullet weight & bullet ogive variation, then it's interesting to see the effect on velocity (pressure) variation.
Personally, I like to know velocity/energy for the different powder levels, plus it's a nice check to see this compares to powder company, ammo manufactuer specs. Plus I had big differences is velocity spread with my expensive Lapua brass (worst case was up to 30-40 fps, with the TTSX) but the once fired Lake City was perfect (under 10 fps).
I've had great groups before doing the OAL-ogive, chrono etc but even if you don't chrono the OAL-ogive test makes a big difference and can save wasted shooting (barrel life). The comparator and measuring chamber is really easy (I had mine for over a year before I finally used it). Now I wouldn't load test without it.
I can't really focus and might sound all over, just had baby number 2 recently...
