Now i know i cant have all the recipes. So that being said, you should be limited to 1 per level and at level 100 you have 100 recipes in that 1 skill.
Considering architecture is going to have several hundred peices by this winter. (new roofs,floors,ramps, bridges,second stories,stairs etc. And the ability to unlearn and learn a new one Id say this is fair.
You worked for 100 you deserve 100 recipes. However Their should be more benifit of a level 100 skill besides quality. What is your opinions? Please keep in mind architecture will Have hundreds of recipes very soon.