Hi insideru,
Yes, that's intentional and that's the way how it has been. If you update one ARCHICAD instance and continue working on the TW project, you'll get a prompt saying that now you are about to increase the Build number of that TW project. If you proceed, then all your colleagues working on the same TW project will also need to update their ARCHICADs.
Increasing the project's build number is a safety mechanism that makes sure to avoid any incompatibility issues that might arise between the older and the newer ARCHICAD instance working on the same project.
The thing we changed in v21 and newer, is that you don't need to update the server at the same time as the ARCHICADs.
Csaba
Csaba Kézér
Director, Global Customer Support
Graphisoft