Same cultivar, same balcony, same amount of sun. Three changes, one of them ridiculous, together tripled the yield.
In week four, I removed every flower bud for two weeks. The plant spent that energy making branches instead of fruit, and every branch became a fruiting site. Counterintuitive until you count: the plant that kept its first flowers put out maybe a dozen peppers on short stubby stems; the pinched one had three times the structure. University extension articles describe this for bell peppers — it works on tiny chilis too.
Balcony four floors up = fewer visitors. A cheap watercolor brush, swirl each open flower mid-morning, done in two minutes. The hand-pollinated trusses set almost 100% versus maybe 60% on the control trusses. In high humidity pollen goes sticky and pessimistic; the brush apparently talks it out of it.
Concrete at 46°C in August cooks root zones. $3 plastic lattice shelves keep the pots 12 cm up, and the difference in the fruit set during the heat wave was the largest single effect of the three. This was the change with nothing clever about it, which is why it's listed last, like all the useful things in life.
Next season note: the plants survive winter indoors by a window; year-three plants get their own article, along with the aphid infestation I am currently negotiating with.