This is getting to be cliché. “While they are dormant through winter”, plants tolerate all sorts of abuse that would offend them at any other time of year. It applies to planting bulbs and bare root plants. It also works for pruning deciduous fruit trees and roses. It is a predictable seasonal pattern. Most winter gardening is contingent on dormancy. Processing potted plants is no exception.
Plants that have gotten too big for their pots should be replanted into larger pots. Any circling roots should be severed, just as if the plants were going into the ground. Unlike planting into the ground, potted plants require artificial media, known simply as ‘potting soil’. If larger pots are not an option, overgrown plants must at least be pruned to stay proportionate to their confined roots.
A plant that has been in a pot long enough for the media to decompose and settle might benefit from being ‘stuffed’. This involves removing the root mass from the pot, adding just enough media to the pot to support the root mass at the desired level, replacing the root mass on top, and then adding more media around the root mass to fill the pot. Exposed surface roots can be buried too.
Many overgrown succulents (not including cacti) can be replanted lower instead of higher. If settled, more media can be added on top. If all the foliage is clustered on top of bare stems, the stems can be cut and ‘plugged’ as new plants into pots of media, while the old roots and basal stems can be left to generate new stems and foliage. Newly plugged stems will generate roots by spring.
In the processes of potting, stuffing and plugging, while pots are empty, it would be a good time to scrub away mineral deposits from the bases and inner rims of pots. These deposits tend to accumulate just above the surface of the potting media, and where pots sit in water that drains from them. The pans or saucers that contain drainage water also accumulate mineral deposits. While plants are being processed, they can be groomed of deteriorating foliage and other debris.