Nothing is set in stone in boxing and all fighters are different its mind less to put every fighter into a should do or dont do category.

Thats why some fighters who have an extra strong side through what Scrap calls a dominant eye are stuck with their body compensating for it. People are not all the same in make up, their are some rare blessed people who are ambidextrous ad their are some well trained fighters who know when allow it.

There are degrees of switching in boxing there always has been like or not it occurs naturally an when it does you can use it or waste time by getting back into your 'chosen stance".

That situation is when you dont actually switch feet, but your opponent moves from one side of you to the other side of you.

If you dont adjust your feet fully and turn your upper body to follow them from their point of view you have switched without even moving. A great boxer can use that to his advantage by shuffling forward into their center line while they move and it cuts them off faster and catches them dead square as you close on them.

Watch Tyson very close in his prime he did that all the time right on the opponents reaction to being hit or swarmed, he as good as switched feet to cut off the ring and cut off their escape routes he did more than go dead square, watch his feet closer next time.In relation to where the opponent was heading, he would move into someones center line and knock them clean off balance catching them flat footed right at the right time, left foot forward or right forward no care to him at all, the job was getting done when it had to be done.