Not sure if you're trying to criticise our waste management, but the point being is we generally fill (by fill, I mean still being able to close the lid) our waste bin after one week and so do you, which means we need a bigger bin for two weekly collections to work without having black bag side waste.
Judging by many bins I see that are put out each week with lids that don't close, this will be more of an issue for many, which is why I raised it.
It's reassuring that the council have already considered this impact and are acting on it.