It is more likely that future evolutions exist on both paths.
One of Each (Three) One of Each (Four) One of Each...
Two of Each (Three) Two of Each (Four) Two of Each...
Three of Each...
Vertical progression is more straightforward but more laborious.
Horizontal progression is more difficult to discover but requires less when discovered.
Admittedly, though, considering that we got Found [...] x 3, we will probably jump from One of Each (Three) to One of Each (Six) which would keep the difficulty ratio balanced.