Q.christmas cactus repotting
Should a very large Christmas cactus be separated and repotted? My Christmas cactus grew very large. Should the be separated and repotted?

It all depends. Christmas cactus thrive better when they are slightly root bound in their pot. However, you should consider re-potting when the roots grow too large for their pot (one tell-tale sign will be roots popping through the drainage holes of the pot). Christmas cactus typically only need to be re-potted every 3-4 years. The best time to re-pot a christmas cactus is after blooming ends and the flowers have wilted - it should never be attempted while the cactus is actively blooming.
If you do decide to pursue repotting, you can find more information here:
https://www.gardeningknowhow.com/ornamental/cacti-succulents/christmas-cactus/repotting-christmas-cactus.htm