Hi darkosaric, i will post some links that have helped me very much concerning split grade printing.
It all started with an old forum post here on apug.
page 3 has a post by bob carnie (post #26) explaining in detail a similar, but different approach.
here is les mcleans very well detailed with photo examples approach
^ this one is awesome, it has helped me out so much.
The difference between that and what i do, is i use 1/3 or 1/4 of a sheet of paper. when i use a 0 filter, and when i use a 5 filter. After i pick a combination, i do a whole print as stated, followed by a hopefully final print that is dodged and burned.
While i became proficient at guessing which filter i needed, with what times, the above method almost ensures, that you won't waste more than 3 (4 if you mess up) sheets of paper.