It should be added that, for correct readings with spotmeters, they should be shaded just like camera lenses to prevent flare. Better ones, like the Pentax, have multicoated optics. But that is not enough by itself if facing the sun or bright reflections. Mine also carry collapsible rubber lens hoods.
The advantage of spot meters in relation to high contrast snow scenes etc is that you can compare distinct high value and low value readings and strategize from there, based on the dynamic range of your chosen film. For example, there are numerous times I've had to deal with bringing out the brilliant specular sparkle of ice or snow, which still needing to bag the distinction between black volcanic rock and little black dark pits and cracks in it. In open sun, especially at high altitude, that can easily become a 12-stop problem, and not just any black and white film can handle it. But even with the longest scale ones, you still have to give careful "placement" of key values.
And with color film, especially chrome, something is going to have to be sacrificed - either the shadows or the highlights. Or else, just move along, and look for a more suitable shot. This amounts to much of my life outdoors. It's ludicrous to defer to fill flash or imagined film "latitude" under such circumstances, especially if the anticipated outcome is an equally rich and nuanced print. Exposure needs to be on target in a manner mere averaging is incapable of.