I think you need to sit down, look up the definitions of the words you are using (postbacc, SMP, masters, degree) and describe things more precisely before you will be able to get any sound advice from these boards. Phrases such as "post-bac masters (SMP)" are incredibly confusing because those terms largely contradict one another (especially given the time description you follow up with).
As a quick overview:
Postbacc: Any undergraduate-level classes taken after graduation from college. These DO affect your AMCAS gpa calculations and can also be seen separately by adcoms (gpas are divided by year: freshman/sophomore/junior/senior/postbacc). This could be one class or many. You can take them piecemeal (DIY or informal postbacc) or as part of an official program (formal postbacc)
Formal Postbacc: A series of undergraduate classes designed for premedical students. Often these include the prerequisites and the programs are intended for career changers - these programs often do not accept students who have taken many med school prereq courses. Others are for GPA repair. These programs are usually 1-2 years long, require application, charge a set tuition (usually very pricy) and
rarely have linkage or special consideration from their associated medical school. They affect AMCAS gpa
DIY Postbacc: Any set of undergraduate courses taken after graduation, typically in a pay-by-course fashion, from any combination of schools. This is less structured, requires no application, and never has any sort of linkage, but the scheduling and payment structure can be better for working folks.
Masters: When used alone, this usually refers to a standard graduate school program. Typically on SDN this will be a research-based grad program, but can also refer to some specialized programs such as MPHs, etc. The GPA from these programs does
not affect your AMCAS gpa (though it will be listed separately) and tends to be given low weight by adcoms due to varying rigor across the country and low familiarity (among other things). A low grad GPA can hurt you, but even a great one will not do much to offset poor undergrad performance. Generally the consensus is, do a masters if you would have done it anyway (aside from getting into med) or if it factors into the future career track you are considering in some way. Duration variable; some MPHs are a year, other masters can last several.
SMP: While this is also technically a master's program (special master's program), it is the exception to the rule above: these programs can strongly help offset a low undergrad GPA. It is essentially 'do med school to prove you can do med school'. Often, people will take courses alongside med students. However, do poorly in an SMP and you are basically done. Many of these programs have linkages to their med schools (or at least interview consideration). The price tag, however, is pretty hefty. These are pretty much universally 1yr programs.
Aside from that: med schools
will see all undergraduate coursework and the grades. If you do a formal postbacc and drop out partway through, they will not only
accept all of the grades from it, but you would be unable to prevent them from seeing it if you wanted to.
However, they may also see that you started the program and backed out, and will likely not be appeased by finding out that you began the program
intending to leave before completing it. So keep that in mind. If you're just taking a year of classes as you go (informal or DIY postbacc), you're not leaving anything unfinished, and you can continue to take classes after the master's as well, which will also count. I can't see why you'd do that, but sure.
Beyond that, I'm honestly baffled at how you could turn a postbacc and a one year masters (or SMP?) into 6yrs. Sure, the grades will count, but your pace will still be visible to the schools, so if you're going easy on the classes, you'd best be doing plenty of other things with your extra time. If you're just endlessly pulling your GPA up, well...at some point you just content yourself with showing a strong trend and call it good. My GPA is not particularly strong going into this app cycle, but I decided to go ahead anyway instead of continuing my DIY postbacc. I could continue trying for years to pull my GPA into a comfortable range, but everything else has come together for this year and I figured that 2yrs of 4.0 postbacc work was sufficient to show that I have turned myself around academically, even if my average doesn't reflect that yet.
As for the masters...if it's truly an SMP, I'd ditch the postbacc, personally. An SMP is the hail mary of GPA compensation...it's what you do when you can't bring it up. Doing both seems wasteful to me. If you're actually talking about a regular master's program, again, it probably won't help you much med-school-application wise, so make sure you're doing it because it is important to
you.
Hope any of that is relevant to your situation - again, it's very difficult to parse out what is going on from your description. At the very least, I hope seeing the terms broken down like that is beneficial. Good luck!
