Why do this, since even stock plans cost you at least a couple of hundred dollars each? Because the right stock plans can save you tons of time and money if you have a talented architect. Most plans are at least partly modular these days, and often you can even order prefabricated sections pegged to a specific house plan.
Every set of custom house plans includes several items which need to be blown up and detailed for further clarification. If a set of plans does not provide additional close-up drawings (for things such as beam connections, deck railings, stairway construction, etc.), then it is not a complete set. It is very easy to cut corners during the planning process. But the end result will be higher costs for the home owner - and lots of frustration for the building contractor.
On the other hand, stock house plans are substantial past drawn designs by a skilled designer or architect ideally of a specific purpose or general use. The question is, why choose a stock plan over a custom drawn plan? It all amounts to various reasons that are discussed below.
Having a custom drawn designed house means a professional architect applies his skills limited to the individual homeowner's needs or what they have in mind. Factors considered in such a situation are the size of the site of construction, ideas of the individual homeowner, population around the area, and the nationally and locally existing building code plans. Time is also a considerable factor for completion of a custom designed house.