Or is this any simpler?
One of the hazards of taking any closer look at almost anything in the city is that everything is so richly connected to so many other things in so many different ways as to make a mockery of the idea of "simple" or even "simpler."
Take, for instance, delis, not in the original, literal sense, from the German, delikatessen, "delicate food," "delicacies," but rather in the more contemporary sense of a small grocery store, often, though not always, on a corner, and often, but also not always, with some facilities to provide hot and cold take out, however limited the menu may be.
The first one of these you encounter walking up Tenth Avenue is on the southwest corner of 28th Street — this surely says something about how little the stretch of the avenue up to there has been residential or even commercial (as opposed to industrial) for many decades now.
The last deli before 110th Street is just above the northwest corner of 109th Street.
In between there are another 34 delis, for a grand total of 36 on Tenth Avenue up to 110th Street.
Or a bit over two per block above 28th Street.
Of these 36 deli enterprises, 16, or 44% were either new to the location (just a couple) or showed some combination of new awnings or new signage, usually with a new name for the business, 2010 vs. 2006.
44%! Nearly half, in fact!
That's a little over 5 per year, 15% annually, meaning, on the math alone, that these changes happen about seven years on average. (Yes, the sample is too small to say this with any certainty, but still, it gives a rough picture and, better yet, raises some questions.)
The first question is this: do the new awnings, new signage, new names indicate new ownership, or at least new management? Meaning, per the numbers, that delis change hands on average once every seven years?
Or are the visible changes just the result of the same owners or managers dressing up the business to keep pace with other changes, especially, no doubt, demographic changes, in their immediate locale? In which case, the question is whether the rate of neighborhood change is such as to motivate such changes every seven years?
Or both, of course.
In short, do changing deli facades, awnings, names, signage give us a kind of neighborhood-intrinsic "clock" against which to measure relative rates of change in the characters of neighborhoods?
These are not questions to be answered by looking at pictures, or if they are, I don't know how to read the answers from the pictures.
Would it be worth going back and asking?