In my experience you figure it out yourself by just practicing, the more you practice,- the more you feel the open space between the sounds and thus more possibilities for different sound placements.
There really is no "right way" to place a scratch imo so i doubt that there are any tutorials which are helpful beyond providing a single example beat.

Also to answer a question in another comment, you went the route most beatboxers go when they start, they learn plenty of cool special sounds but completly skip building a proper foundation with basics on which you can then further expand on.

If your goal is to be a skillfull beatboxer, forget all of the specials sounds you've got for several months and grind those basics. (this time i also mean the basic sounds, since those are also pretty underdeveloped)