@Nate Oosterhouse
Hi Nate,
What I generally see (and recommend) is that success is defined as the lead achieving the intended goal of the marketing initiative, defined tactically within the context of the channel.
So when you deploy a webform, the goal is for someone to fill it out.
When you hold a webinar, the goal is for someone to attend it (either live or on-demand).
When you send an email, the immediate goal is typically clicks, although sometimes a company will be a bit more stringent and require some kind of subsequent form fill in order for the email to be considered successful. I tend to think a click is the most reasonable gauge of success.
I would avoid trying to define success differently for different leads based on their lifecycle context, as it starts to define success more in terms of upstream or downstream lead behaviors rather than reflecting how they engage with your specific marketing initiative, which is the intention of program stages.
That being said, I don't think it's bad to add stages beyond success to help track at a glance any leads that reached success and then did something else (e.g., reached MQL, closed won opp). The main requirement here is that all subsequent stages must be success stages as well and must be a subset of the previous stage - e.g., a program stage of "Sales Accepted" on a web form program means the lead filled out the form AND was then sales accepted.
This way you can still get a clean read on how many people reached your most fundamental success step.