I don't believe having monthly work is better just my opinion,ok it may mean if you do 2 and 3 monthly work you'll need 2-3 times the work but it is far easier to organise and you can price higher due to not being on there doorstep what seems like every other week in there mind. When I turn up on a 2-3 monthly job you can really see the difference when you've finished cleaning them over a monthly clean,I've done lots of monthly stuff in years gone by and I've always felt rushed to get round to doing them a month just flys by in this job,much more profitable to say it'll be 40 every 2-3 months rather than run your arse off for 25 on the same job,in my experience people don't mind paying more for longer gaps between cleans and lets be honest do they get much dirtier,not really me thinks in the grand scheme of things it's not like they've not been touched for 3-4 years.