I believe it makes a difference on what you mean by "changes". It is possible to edit an "Add Assignment" control and change the text in the description without disabling the process. However, in practice its quite probably that anyone inside of LDSD will get locked up and/or kicked out. So in general it's not the best idea to make changes with users in the system. You mentioned Assignment4 and that is a window. If you make changes to this window, typically the really bad things don't happen. However, they also tend not to have any effect unless you recycle to app pool or do an IISRESET.
It's best to set aside maintenance time, deactivate your process if needed, recycle the pools if needed, and then let everyone get back to work.