Sealant can definitely be a practical short-term solution, especially if you catch those cracks before they turn into bigger problems. I’ve seen it hold up surprisingly well through a couple of rough winters, as long as the damage isn’t too extensive and the roof’s pitch isn’t too steep. Like you mentioned, climate really does play a role—up here in the Midwest, freeze-thaw cycles can sometimes push sealant past its limits, but for minor cracks or small leaks, it’s bought some of my tenants an extra season or two before we had to do more serious repairs.
I wouldn’t rely on it for major damage or as a permanent fix, but if you’re not ready to replace shingles (or the whole roof), it’s a reasonable stopgap. Just make sure you’re using something rated for roofing and check it after heavy weather. Sometimes folks forget about those quick fixes until water starts showing up inside... and by then, it’s a bigger headache.