This idea is important to save money for councils, maintain the right for licensees and residents to apply to the licensing committee but stop business conducting a legal 'war of attrition' on residents.
At the moment pubs and bars can apply as often as they like for things like longer opening hours and permission to play music etc. This means that if local residents object and go to a licensing hearing and show there are real problems being caused by the activities of the pub/bar and prevent the changes requested, the licensee can just start the whole process again straight afterwards. It costs a lot of money for councils and licensing committees to repeat the proceedings again and again and also means any objectors have to take more time off work to go to more hearings etc. It seems that the repeated applications are made so that eventually the amount of residents objecting reduces (as they can't keep taking time off work) and the likelihood of the application for extended hours etc. being granted increases.
If applications for variations of licenses were only allowed once a year then a lot of money and invonvenience would be saved without removing the right for a licensee to try and extend their license at a later date.