If you were really careful, you would use a "stack discipline" in 
your day to day development, too.  That is, the ideal thing from 
Monticello's point of view would be that, every time you started a 
new set of changes, you reverted back to the earliest version that 
could support them and continued from there.  If the next changes you 
make are unrelated to those, you revert back again and branch.  Then 
if both of those changes are required to do the next changes, you 
merge the two resulting versions and use that as the baseline going 
forward.  But you shouldn't do them linearly, because that implies to 
the versioning system that the second changes are dependent on the 
first, and you'll have trouble if you later want to use them on their 
own. Now, I don't do this much in practice, because it's a hassle, 
and not the way I'm used to working.  But it would be interesting to 
see if this awareness of the dependence and independence of sets of 
changes could be integrated into the development environment well 
enough that it was a natural and pleasant way to work.