Five years ago I had an architect draw some plans to remodel my house. We never did the project. It is possible. The key is if your plans are now appropriate for your market. Incremental design and designing the house around imaginary walls.
Incremental design means the design starts out at one level and then continues to evolve.
For example, a budget room addition begins to grow and custom home features begin to be added. The result is a home that has the floor plan of a budget remodel, but the finishes of a custom home. Architects often design with the idea of keeping certain walls to save money. In practice, however, the contractor plans to demolish the walls because it is cheaper for him to rebuild. By knowing, in advance, if the walls should be demolished, a better design can be obtained.