Winters are a bit harsher here than what I've experienced on random visits across the pond. We can have long stretches of subfreezing temperature (we take -5° in stride, -10° is not shocking). Similarly, snow can stay on the ground for weeks. We do have thaws from time to time, and +5° is not uncommon, but it's not the norm. Days that would actually be pleasant for running trains (i.e. over 10°) are rare.
On top of that, for the sake of the garden, I let the fallen leaves remain for the winter. They both protect the plants, and their decomposition helps the soil. If there were more pleasant train days, it might be worth clearing the tracks, but given the weather it hardly seems worth it. So I just don't run.
I actually enjoy the seasonal rituals that accompany the railroad. In a few weeks I'll collect all the figures from around the line, take them inside, wash them off, and put them in storage. (Buildings stay out all winter.)
The first mild weekend in March, I'll go out and clear the dead leaves. Finding the newly sprouting plants underneath is always a pleasant harbinger of spring. At the same time I'll reballast, and fix any track joints that are causing voltage drops. Having to "work" on the railroad makes it more real to me.