How Long is Too Long?

I got your attention with the title, yeah?
In my wickedly deviant brain, there is no such thing as too long.

However, according to Rebecca the Bookseller at the Lipstick Chronicles, a little blog I visit on occassion...
there is an ending point when it comes to the Series question. So, in the hopes of gleaning enlightenment, I read the post and came up with inconclusive data. However, it did scream for me to dedicate more attention to this little before thought out question.

I've never embarked on a series before, now I have:
The Chronicles Of Surrender.

As of a few short months ago, I pitched it as a three book series:
Sacred Secrets
Unholy Promises
Forgiven Sins

And then the series morphed...Unholy Promises became Book 3,
not Book 2, Book 2 is currently awaiting a title, its working title,
SSR (Sacred Secrets Revealed) uninspiring, but brings us to
Book 4 Forgiven.

Ahem, news flash, after a short discussion with my editor today
about expanding on a small part player in Book 1, we now have
Book 5 Hallowed Screams.

I wish the Lipstick Chronicles had clarified, because there's this
secondary character in book 3 who really needs to tell his own story...