I used to always dynamic time my engines. I think this is required for "race tuning". But, I can't tell the difference with normal street riding and have gone back to static timing.
Dynamic timing can be a real (insert curse word here), in order to get the proper timing along with ideal dwell time for the coils. (Speaking about points set ups) The gap sets the dwell time (Coil charge up period), and the points pair rotation around the point cam sets the timing. But, they can be interactive, particularly when the engine is running. This is because the point springs exert pressure between the large plate and point cam And while it is loosened to adjust time, the plate can shift in its mounts not only about the cam circumference (desired), but side to side and up and down as well (not desired). This often causes the dwell/gap to change while hunting for correct spark time. It can be done, but it takes some thinking, anticipation, or coercion to get it all perfect. And in the end, static time works as well as dynamic for 95% of engine operation, (unless, of course, you are spending 90% of your engine run time up near red line).
With a bit of practice and diligence, your static time will equal dynamic time in nearly all attempts. But, I will mention is that it is very important to have the 1,4 set align with timing mark identical to the 2,3 timing mark. A timing mismatch here will show up as uneven idle.
Cheers,