As long as it is a "normal" situation, like 38 special in a 357 revolver, 44 special in a 44 magnum revolver, or 32 S&W (or more often 32 S&W long) in a 32 H&R magnum or 327 magnum revolver, there is no problem.
I do it all of the time. Most of my higher-powered revolvers listed above shoot the lower-powered cartridges more often than not.
After my range sessions of 50-100 rounds per revolver, I spend something like two minutes cleaning the cylinders of each one. That's it. And I never have problems.
Apparently some people are too lazy to clean their cylinders, or enjoy spreading misinformation.
(I don't mean THR members, but some people somewhere apparently repeat nonsense about this subject to new revolver owners.)