Simply to show how many of these tiny parcels there are - this is an overview of Gothenburgs (Swedens second largest city) kolonilotter and the numbers show that there are multiple of them in that area:

Notice how the numbers shrink but the dots increase as you zoom in:

Source: https://goteborg.se/wps/portal/start/bygga-bo-och-leva-hallbart/bostader-och-lokaler/koloniomraden-och-odlingslotter/hitta-koloniomraden-och-odlingslotter/?view=map

Personally I’m a bit too introverted for the socialisation that kolonilotter means but I love the idea behind them.