Merriam-Webster and others have a definition of an era as, "a period identified by some prominent figure or characteristic feature", "a memorable or important date or event" or "a fixed point in time from which a series of years is reckoned" or "a stage in development (as of a person or thing)".
(
https://www.merriam-webster.com/dictionary/era)
I think the word "era" makes sense if you describe a period that has come and gone, that's never coming back. Based on that, it doesn't really make sense to call runs in Spider-Man "eras".
Eras in Spider-Man:
-- AF#15 to ASM#28, i.e. High School Peter. That's gone and that's never coming back in 616 Marvel. At least not without a substantial reboot and change.
-- ASM#122 to ASM#290. Gwen dies, the end of the Lee-Romita era of innocence and the most charismatic period of Peter's supporting cast. Eventually led to Peter leaving Harry's loft and going to an apartment in Chelsea which remains his "pad" for the next 200 issues or so.
-- The Spider-Marriage, i.e. Peter and MJ get married in ASM Annual #21 and that era defines Spider-Man for 20 years and literally still defines and colors Spider-Man because the continuity is still defined by its absence as much as its presence.
-- Within that, the Clone Saga and its aftermath qualifies as a sub-era. Because it was a period of such distinction and disorder which affected the titles for such a long time.
-- JMS' run is unusual in that it feels like an era in retrospect, i.e. the last time you have a writer approach Spider-Man as a grown up adult hero with character development and change. Since JMS, no version of Spider-Man, in comics, in adaptations, has appeared with as much maturity.
-- Of course OMD to the present is an era.
I don't think BND, Slott, or (provisionally) Spencer's run qualifies as an era, because the stuff that happened in their runs didn't really create any changes or actions that will last or is built to last. Almost everything in Slott's run was mightily swept away in Spencer's first issue. OMD still remains the most defining story in the current era of Spider-Man far more important and consequential than anything in BND or Slott, and presumably Spencer's run for the time being.
Your post was in fact completely vague and incoherent in terms of defining what an era was and how you categorized it, using private definitions that nobody else, here, recognized or acknowledged.