Judging by the social media feeds of many significant poets and prominent publishers, there seems to be a tacit admission that they both believe a full collection's commercial life pretty much comes to an end on the day it's launched. Or at most, the book's life is drawn out till the appearance of any reviews a few weeks or months down the line, never again to be mentioned in commercial terms.
This attitude is patently leading to a lack of medium-term sales. A full collection needs exposure over a period of time so as to enter into a potential reader's consciousness. From my own experience, for instance, I've witnessed the gradual growth of a vibe around a book if a continued effort is made to explain and sample it. I've personally sold over forty copies of Whatever You Do, Just Don't (HappenStance Press, 2023), my second full collection, so far this year, a major chunk of them via social media, even though the book is now eighteen months old. But the most striking thing is that this interest has also generated a synergy with my 2017 first full collection, The Knives of Villalejo, which has also contributed a further twenty copies to my sales figures.
The above-mentioned story leads me to believe that a full collection's commercial life is actually as long as the poet and/or publisher wish to make it. By immediately moving on to the next creative project, poets lose out on readers for their previous work. And by concentrating on driving a constant churn of new titles, publishers miss out on sales. Mind you, a further question in many cases might be whether their focus is more on funding than on shifting units.
In summary, readers are our lifeblood and we should never turn our backs on them. And in that same vein, (plug, plug, plug!), you can get hold of a signed copy of Whatever You Do, Just Don't by dropping me an email at the address that appears in my blogger profile! Thus contributing to prolonging its life even further! I look forward to hearing from you, etc, etc, etc...!