There is lots of guidance about DPS' on local authority websites such as
http://www.scarborough.gov.uk/pdf/DPS%20Fact%20Sheet.pdf The following are lifted from the above:
"The Licensing Authority hopes and anticipates that that the DPS will spend a significant amount of time on the premises, as the guidance suggest that the DPS should be someone who has ?day to day responsibility for running the premises?."
"... if you are going to be the DPS for more than one premises, you would need to carefully consider whether you are able to fulfil the requirements laid down in the guidance."
"The DPS will be easily identifiable, as both the Premises Licence and Summary (this is a shortened version of the Premises Licence) specify the name of the DPS. The Summary of the Premises Licence has to be prominently displayed at the premises."
You can have several Personal Licence Holders but only one DPS and each premises should have a premises licence detailing the hours they can open etc.
Each of these has a cost implication, hence Humph's reluctance to change anything. The premises licences, are nearly all from the previous licencing laws when the old opening hours just moved across. I've been told that to change these can be quite costly and may involve use of a legal company. Also probably accounts for some differences in all day opening at weekends.