Lesson Planning...

After reading and commenting on a fellow classmates' blog about PACE in teaching, I am in reflection about lesson planning.  This spring break I have been in the classroom a couple of times preparing some lesson plans for the upcoming 4th quarter.  In planning, we teachers certainly "guestimate" how much time an activity is going to take - but we don't really know do we?!  Of course, I always plan more than less but how can we put a time limit on a particular unit of study.  I don't know about anybody else, but I always seem to feel rushed at the end of the school year trying to finish up a text book or unit.  Am I really doing justice to the subject area if I am doing that? What do I compromise in my classroom and take out of study if need be?