We all wonder how much to push our dc in the things that are not their favorites. Then we worry if we don't, what is the habit that is being formed?

I wish I could tell you this would go away as your dc get older, but it doesn't - it continues on. From everything like chores, morning routine, bedtime routine, table manners, acceptable behavior, character training - and yes, school too. I can't give you a set answer what would be best, because only you will know in your own home what habits you are focusing on instilling, and what battles you are waging. I can share with you some Charlotte Mason quotes that have helped me through tough times with my dc:
"The formation of habits IS education, and education is the formation of habits." (Vol. 1, p. 97)
“It rests with parents and teachers to lay down lines of habit on which the life of the child may run henceforth with little joltings or miscarriage, and may advance in the right direction with the minimum of effort.” (Vol. 1 p107)
Here's one comical quote from Charlotte Mason that makes me laugh out loud

, because I am reminded of this daily in my house!
"The mother who takes pains to endow her children with good habits secures for herself smooth and easy days; while she who lets their habits take care of themselves has a weary life of endless friction with the children: All day she is crying out, 'Do this!' and they do it not; 'Do that!' and they do the other" (Vol. 1, pp. 135, 136).
Now, how true is that?!? Doesn't Charlotte Mason have a knack for hitting the nail on the head?!?

We all long for the smooth and easy days she speaks of - and just when we've reached them, it seems as if another habit has arisen we need to deal with.
I was thinking one thing that might be helpful for me to share is the progession I've seen in my own dc as we've gone through the various HOD guides - maybe that will help in your decision some...
In LHTH, the Fingerplay emphasizes one letter and its sound, while also reinforcing the Biblical theme, and every 5th unit is a letter review unit. In LHFHG, A new rhyme is introduced each unit and each rhyme emphasizes one or more gross motor skills, and also reinforces the history theme. By Beyond Little Hearts, the rhymes are replaced with poems, and a different classic poem is introduced each unit. The poems also reinforce the history theme. The active part that dc did with the rhymes/fingerplays is transferred to Bible where dc put actions to their Bible verses to help them memorize them more proficiently. This is continued all the way through PHFHG, at which point the Bible verses are much longer, and lengthy passages of Psalms are memorized. Both of my dc often choose actions they already learned from doing the fingerplays/rhymes for memorizing their Bible verses. When my oldest ds did PHFHG, he relied on these actions (as well as the Corresponding Music) to be able to memorize the long passages.
So, in closing, I can't tell you what would be best for your situation. I can tell you that from what you've shared, it's obvious your heart is in your post here, and that you are weighing what you need to expect of your dc carefully to make them successful. It is my prayer that it be made known to you which habits are most important to work on for each of your dc, and please pray the same for me, as I wonder this each day as well!
In Christ,
Julie