Why does everything take so long?

Made a start on the Detail Survey today, and what I thought was easy is turning out into an epic!
Found out I made a big blunder - the OS map had what looked like building shapes to the rear of the Garden Nursery, in my detail area. Only when I have started drawing up I realise that they are infact related to NOTHING! So its back up to Hadlow tomorrow to fill the VOID that has been left!