The Big Base
Think of your training as being like a pyramid. If you want the peak of the pyramid to very high then it needs a big, solid base. The basic off season approach of “getting the miles in” has been tried and tested over many years and it works. It doesn’t mean going out with a chaingang and having a mock road race every Sunday during the Winter, hanging on for grim death until you eventually get shelled out and make your weary way home on your own. It also doesn’t mean sitting in a large group of riders hardly making any effort at all.
It means getting out with a reasonable group which suits your ability and doing some steady zone 2 and 3 rides. That means that it shouldn’t be eyeballs out all the way round but you should have to concentrate to maintain the effort while still being able to hold a conversation with your fellow riders. Have a thrash up the hills later in the Winter if you like but don’t let the effort level drop too low on the flat.
If you normally wear a pulse monitor for racing then you can estimate your zone 2-