you might try maybe changing Clicks to another value which is by default 96.
So if separators are at 4 * 96 = 384, and you want instead 3 * 96 = 288 (do
you want to create waltz or jumpstyle or hardstyle or schaffel or what?),
you might try 288/4 = 72 for Clicks, so defining
Clicks = 72
Then the gap among those separators would be at least what you want, but of
course this changed Clicks parameter might have other negative side effects
which you do not like? Just an idea to play with.
Then for each quarter note you should use instead a triplet, meaning a
duration of 72/3 = 24.
Best greetings,
Tony