So I had interesting results with this. FLTS ON seems to give both FASTER and BETTER alignment results.
TLDR; Same set of 7148 JPGS got 6% more images aligned in 10% less time with Fine Level Task Subdivision turned on.
I was benchmarking DNG/JPG with FLTS OFF and 7148 images. DNG aligned 6909 (5:28:19) and JPG aligned 6550 (6:50:03), which bummed me out because DNG was better and faster (but 16-bit and waay bigger files). Interestingly a colleague who had the same set as me and a machine that ran slower than mine in other benchmarks ran the DNGs with FLTS ON and got comparable timing (5:28:01) and 6981 images aligned. I decided to try the JPG again (copied the chunk into the same project, reset alignment, ran with FLTS ON, and got 6925 images aligned (6:10:10)