Its hard to wrap your head around at first . But think of it this way... the MSD ( in my case Daytona Sensors) cant see into the future . So you advance your timing then it retards it at idle and brings it back in as the rpms increase.
Thanks for all your posts guys I’m sure I can manage from here looks like I will be ordering a timing tape. Looks like the old saying “necessity is the mother of invention “ applies here.