Perhaps it would be useful to be illustrative.
Toronto once was a 15-minute City; all that is being suggested is to return to that.
View attachment 456799
Excuse the blemishes...... as you can see, this area of East York is served, today, by 1 full-service supermarket (chain).
In the 1950s it was served by several more, of which I've highlighted but 4 (there was an additional one on Donlands, for sure, and I suspect others)
Today, this area has zero operating cinemas. The star I placed shows one former location (Roxy); but there were also cinemas at Danforth/Coxwell, on Donlands by O'Connor and on Woodbine near Sammon.
The 15-minute city means nothing more or less than trying to recapture what we never should have lost.
If you cap the size of supermarkets at ~30,000ft2, you would essentially divide each of the Metro and Loblaws at VP/Danforth and VP/Gerrard in 1/2. Recreating two additional locations.
If you modestly grow the density to support more retail; and break up the oligopoly in grocery, you'd get get a couple of more in this area.
***
We won't ever go back to one-screen cinemas on every second block, but its entirely easy to imagine one or two built within the right developments, likely next to Line 2.
That's the 15-minute City in a nutshell.
You're not confined to your area; you simply don't HAVE to leave it, just to get groceries.