Anytime house maintenance explains a few of the house components that do not necessarily depend on seasonal preventive repairs. Of course, based on your observation of those components, and their quality, you can implement some kind of a schedule that will help in monitoring and servicing.
1. Change or clean your forced air heating / AC system filter every 1-4 months based on type and usage.
2. Replace caulking / silicon around your tub, shower stall and sink whenever it starts separating from surfaces.
3. Inspect your bathroom tiled walls for cracks and missing grout – fill the gaps as soon as possible to prevent water penetration and tile backing wall damage.
4. Periodically check the main water shutoff valve and individual plumbing fixtures valves – might leak if left untouched for several years, might not operate at all and start leaking if you force them to turn. If it turns freely, open it all the way, and then back up a little – this helps to prevent the valve from being stack.