During his interview with Contact Editions magazine, Chris Dorley-Brown reveals:
"the pictures form themselves into groups and concepts later on and I let them do it on their own; I don't interfere. Usually after a year or two I realise I have been focusing on tower blocks, cars, people, whatever. Then I have a collection, show it and move on. Often I return to previous projects and re-edit, re-shoot, re-interpret them and they become a new work".
Adding keywords to pictures has been inspiring to me in much the same way as Chris describes. Take churches for example:
The St. Andrew Parish Church > ZOOM II Catalogue
Initially, these count as Buildings but then a bit of research determines the style - like Saxon - and you're drawn to the history, which leads to another keyword and a fresh interest such as clerestory windows, providing light and fresh air for the congregation.
Lancet windows are shown here.