Marksman Building?

I have no idea how the method you described works, so I just set level to constant and fiddled around with a calculator, pencil, and paper xD

Looks like this, except since I don't know the Marksman formula I used the Bowmaster one (3.4*dex). I don't think that should change it much.


Green is the highest value in a row (as each row is the total number of SP available for the 2 skills), as you level up you go down the table.
Each column is the number of points in Boost (from 0 at the left to 30 on the right)

The main things I noticed are that pretty uniformly 26-27 Boost is the most you should do until SE is maxed.
Since 6 and 21 Boost are the levels where it gains both atk and mastery, they're also the best spots to leave it.
The difference is never more than about 3-4% in the example I gave, so it doesn't really matter which you do first.

As you can see at the top I have spots to put in skill/dex/str/atk so I can adjust it to fit any skill/player.

 With Eruption (160% base)

 Surface plot for Eruption

 Overall relative strength with Strafe demonstrates how little it matters which you choose first