You can make "easy" splitters for any number you can write as a 2n * 3m (with n and m being integers from 0 to "infinity").
4 way -> Split in 2, split each of those in 2
6 way -> split in 3, split each of those in 2
Any number that isn't 2n * 3m can be achieved by:
Factor the number.
Remove all the 2 and 3 factors. (so 10 -> 5 * 2, remove the 2, hold the 5)
Split the remainder into the first largest number that does follow the 2n * 3m rule (so for 5, that would be 6).
Split in 6, feed the 6th back in, you now have 5 lanes. You can now split each of those lanes by the remaining 2 and 3 factors. (so for 10, split each of the 5 into 2).
The real question is... WHY do you want to even try to split a lane into 5 "lanes that HAVE to be equal. There really is very very little reason to do so.
"load balancing" your fabrication is not needed, daisy chaining splitters works perfectly fine and is a lot easier to set up and manage.