If you have the requirements documented and putting aside the management and other support activities. Technically the ration between System Design, Development and Testing is 25::50::25. The Development will include Unit Testing. This is a standard practice we follow for high level estimations... however the type of applications can make the ratio different.

Great, thank you! I put the XSD file two directories up, so the following two lines now do the trick: DirectoryInfo schemaDir = (Directory.GetParent(Application.StartupPath)).Parent).Parent; string schemaFullName = schemaDir + Path.DirectorySeparatorChar + "OptionsSchema.xsd";

Excellent! I just tried your solution and it works (not being able to edit the projects' properties in the designer view is a bummer, but editing them manually does the trick). Thank you, Phil! Vladimir