Having lived only in places with tile or slate roofs, I can confirm Shessar's photos are indeed entirely accurate for both those materials. Slide, wind effects and thin ice/snow melt basically works from the top down, and outer roof edges facing more nearly into the current wind, so those will all tend to clear of snow first. This can be enhanced around objects sticking out of the roof like chimneys and stove pipes, especially where those are in use. There may also be some smoke discoloration of the snow near chimneys that are in heavy, regular use as well (albeit that also tends to mean snow there will melt faster as well - introducing foreign particulates to the ice/snow helps it melt faster generally, like applying salt to road and path ice).

Roof patches do tend to be harder edged than you've illustrated so far, and with a tendency to remain in the hollows a little longer than the ridges on shaped tiles, as you've already noted. There are a lot of variables however, and commonly, once the snow's started to melt on such roofs, it will tend to clear fairly quickly thereafter, unless there's fresh snowfall heavy enough to fill-in the cleared gaps.

There are things to be said for both options (plus of course, you can't assume everyone will wish to map somewhere where the snow falls in late autumn/early winter, thickens and only starts to thaw around the start of spring - i.e. the randomness of what happens in British winters!), and both are obviously buildings. However, the one with less snow cover has a bit more character to it, which would definitely support the idea you mentioned in your most recent post Sue.

Yeah, I'd settle on one or the other, I think.

The cart tracks look a little more like car tracks to my eye currently, although magical carts requiring no animals to pull them would produce something similar. And if reduced in size considerably, they would work for sledge or ski tracks.

For animal-pulled vehicles though, there should be prints - or more simply for this style, perhaps, simply a muddied/shadow pock-marked region - between the outer tracks.

Sleigh tracks might have a central runner track as well as the two outer ones (actually at the centre-front of the sleigh, but that's not very relevant to the look of the tracks), just to complicate things still further!

Oh, and some suitable carts and sleighs would be nice to have as well. ⛷️

Not merely tin (or other sorts of metal) roofs, but any smoother kinds of roofing material, such as tiles or slates. The idea is to substantially roughen the surface in some fashion - using rocks or logs sometimes (still to be seen in the Alps today in places, for instance). Reason I suggested them is, and depending on the snow thickness, they can break-up the appearance of the smooth surface of the snow seen on the roof symbols currently.

Thatched roofs tend to be pitched steeply enough to shed snow (and water), thus snow shouldn't accumulate as much on them (in parts of Japan subject to heavy snowfalls, the thatched roofs have a particularly steep pitch, for example). This isn't so much because thatch can't cope with the snow or water, but because thatch is usually lighter than other roofing materials, so may not be sufficiently supported by the underlying roof structure to carry the additional weight of substantial snowfalls.