I figure out how much of the end grade I want everything to count. I count formative assessments as half and summative assessments as half - like this:
Classwork/Homework - 15%
Interactive Notebook - 35%
Quizzes - 15%
Final Assessments (Tests and Projects) 35%
I feel that that is balanced - if I used total points I could never be sure that little assignments didn't end up counting more than big assignments. (That being said I have a friend who swearts by total points)
I plug those weights into my gradebook software and that is the last I have to worry about it.
When I add an assignment, I tell the program what category it belongs to, and it does all the math. Yeah computers!
Have we answered your question or are we missing the point?