The bottom line is you need to get 16-20 looks at everything. For covering trees you need to get 25+ views of the treetops for reliable results.
50% overlap in any direction gives you 2 looks at everything.
66% gives you 3.
75% gives you 4.
80% gives you 5.
82% gives you 6
90% gives you 10.
So you could do 75/75 to get 16.
Or 90/50 to get 20 views.
High values for along track overlap will slow the flight down considerably (sometimes that is a good thing).
Slow values for along track overlap will speed up the flight speed but will require more passes to get the minimum amount of required views.
Generally it ends up being a wash but you can tune it one way or the other for various reason.