Yes, however there are mandatory fields, marked using the traffic light system. Green status buttons indicate mandatory/recommended field complete, red status buttons indicate mandatory field incomplete which must be completed and amber status buttons indicate recommended field incomplete. You will not be able to submit your application if you have not at least viewed each page of the application form and/or completed all mandatory fields. Pages with incomplete sections will be clearly flagged on the 'Declaration Page'.
Most firms do not require you to complete every single field but remember, this is an application form and as such you should attempt to answer as many questions as possible.