I'm confused about something. I've always heard that you can tell how
good the insulation is in the attic/roof by how long it takes for the
snow to melt off the roof. Does good insulation in your attic/roof make
the snow melt off quicker or does it take longer?

I tried looking at different roofs in the area to figure this out but
it only confuses me more. For example, my garage and shed still have
snow on them but my house doesn't. Sometimes a neighbors (much newer)
house will have snow on the roof and mine won't have any. Then I look
at another shed that has no insulation and is somewhat in the shade and
it has no snow on the roof.

When I searched on Google, that confused me as well because unless I'm
reading something wrong (I probably am) it's saying that my shed has
better insulation than my house! BTW, the roof of the garage and house
are both facing the southwest and the garage roof is only slightly
lower than the house roof.