The reason your brass needs such regular cleaning is because of the cleaning solution left on it each time it is cleaned
(sigh) it is the soap/brasso/chemical that is used on the brass that encourages the dirt to stick and the brass to look off
Try tomato ketchup or even brown sauce, spread all over wipe dry wipe clean with damp microfibre leave to dry to streak free finish
Next day quick wipe damp micro fibre easy peasy
depending on amount of traffic once weekly with the ketchup
Gordon