Hi fun2lean,
that guilt sounds pretty familiar. Though I do not see it so negative. I love to burn for my pupils and I do not have the feeling to burn out as I get enought "fuel" back from them.
Anyway I know that things will be different, when I am going to have own children. When I plan my lessons, I consider how much of the planning I can reuse next year, so I can save time long term.
Great post, keep up the great work.
RE: Guilt of Teachers