When I am asked to do a "deep clean", I make sure to find out what the client is already doing, so as not to repeat it. Otherwise, what is the point?
Most of the domestic work I do and have always done is on a two-weekly or four-weekly basis, and I go there to have a "good do" of the house, to supplement what the client has been doing. Many working people want the dusting done, but for a lot of older people who are retired, it's to do the work they can no longer do - not the kitchen surfaces, but floors, low and high level dusting, bathrooms, and other things they can't do any more.
For the weekly clients, it's always been more about keeping them going for another week and not much else, as they don't do much in between, and they haven't got the budget or else don't wish to pay for time spent on "maintaining" the house. They just need to survive another week. Granted I've had one for almost 20 years who has me weekly, lives alone, makes little mess, and pays enough to get the house cleaned thoroughly as well as allowing me to do other less frequent jobs, and never cancels when they are on holiday (which can be up to four weeks at a time) so has plenty of time for "deeper" cleaning, but they are rare.
It's like anything, there are great service providers and less great service providers. There is also a wide range of customer requirements and attitudes towards cleaning. As such, it can take any one person quite some time to find a cleaning service which meets their needs.