if too many changes will be done at once then multiple bugs can creep in at once. And in worse case make everything "work" but when you try fix some corner cases then all bugs will surface again in other places.
When we include biggest change and test it fully, then small optimization could be tested locally without worrying that big change could interfere with small one.
btw I do not think merging is good strategy in this case, as I make rebase of your changes, next RC1 will be another rebase (I will push changes on RC0 too but without rebase, for you to see what I changed). I do this mainly because I try with Meridian keep linear hisotry and atomic commits as this allow easy bisection of bugs (as we can find exactly what commit break some mods).
