Well when it comes to long haul outstations which is the subject here it depends on some ability to actually check your bag first before it goes to a bag store - so you need a manned desk able to take BA bags early or some self serve desks able to do the same. So having a bag store at the airport does not automatically translate in to an actual ability to bag drop early with BA.

HKG allowed city bag drop early which the specific facility provided. SIN did pre covid at the airport but I think that was stopped during the pandemic. Not sure if it has resumed now.

Are there many other Asian/Far East outstations which offer early bag drop for BA flights?