most cnc's will hold what ever offset is called and it will stay modal until another offset is called , which is to say that m30 can come up all day long and the offset (g54-g5#@) will not change . But there are a lot of professional cnc's which will default back to g54 once m30 is reached , or the reset is hit or what have you . Many times it can be changed in the machine parameters .
Bottom line is to get in the habit of always having the offset call after each tool call , it's simply the proper and professional way of doing things
A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........