The other option is a spread of the high intensity sessions in the S-to-L program (ie 2 x/wk vs 3)
The question of why S-to-L isn’t used more might be a matter of who acknowledges what they are really doing. Is Steven Francis doing a Long to Short when there is a huge emphasis on short hills (in fact by far the predominant speed vol - 24 x 40m hills) and the “long” consists of rep 300m in 37sec?
What happened with Bolt in his breakthrough year and why did his 100 drop right away and he set a WR before he felt he could successfully run a 200m?