How often do you tweak pages?

[Artecona]

We finally got ranked in the top 20 for some of our top key terms in a pretty competitive industry and are now trying to move up into the top 10 and have a couple questions.

In the time between the major updates will tweaking our pages move us up and down in the serps?
If so how often should we look for changes?

Can a minor change, like the title, result in moving from a position 30 to a position 5, or is it normally a much less drastic change than during the major updates?