I do a full system backup monthly, but never really plan to use this. I use a simple P2P setup, and our main computer runs only a few programs, mainly PM and AC. Because Windows computers accumulate crud over time and slow down, if I were to have a failure or want to move to a new computer, I have always installed a fresh copy of software and then added the data, rather than using the full system copy. It can be done relatively quickly.
Is there anything wrong with this approach?