For an instance Site A as shown in the first photo could be justify as an easy site to get start with as it's already in its ready-condition to be develop.Site B on the hand would need a whole lot more of studies, and analysis and more information on existing inverts, services etc etc as it has a complex condition to begin the design process.An architect would have to lead the site study, get as much help as possible, for example a land surveyor need to be appoint to gather all the information of the existing topography, and a civil engineer would be needed for a study on the hills slope and earthwork procedures.
These all would be part of a process being terms as 'Site Study'