This is personal preference, not facts. I've run personal PCs for years and never turned them off. It has way more to do with managing and maintenance then "should do" anything. I have had the original iPad and never shut it off in between iOS updates, iPad 2 on since March 14th zero issues, no restarts etc... The Xoom only gets turned off if it locks up, otherwise a simple app like System Panel can easily free up memory.
Common sense and a little tech know how, neither of which is taught in school.
The great thing about the Xoom is all the tools available so you can see what's going on, see what's eating your battery, CPU cycles and ram. They also allow you deal with those heavy usage apps and shut them down. Yes I know Android is suppose to deal with them automatically blah blah, blah... It doesn't always do a good job so learn and use the tools to make it run better. Plain and simple.