to remove casing from sausages or not?
I'm sure it's a personal preference.
Personally, I'd never dream of doing it, unless it was for a dish that specifically called for it, or one that requires 'chunks'*. Part of the job of the casing is to keep the sausages moist. You shouldn't even prick them with a fork whilst frying [yet some people do].
For chunks, there's a distinct difference between frying them whole &amp; cutting up than cutting then frying. The first retains the shape, the second tends to squeeze out of the ends as the casing shrinks.