By John Flanagan
Do not use Datum Levels Inside Groups
Datum elements include Grids, Levels, Reference Planes and Scope Boxes. Deleting duplicate levels in a group may also delete content hosted by those levels.
Do not Nest Groups (groups within other groups)
Avoid nested groups that could be nested families instead. For example, if you need a table and chairs, create a nested family instead of creating a small nested group with these components.
Do not Mirror Groups
When mirroring groups, some elements may be reversed. For example, plumbing hot water versus cold water will not be in the correct position. Best practise would be to create left and right versions.
Avoid In-Place Families Inside Groups
In general, you should avoid placing in-place families inside of groups.
Include both the Hosting and Hosted Elements in the Group
If a hosted element is in a group, its host needs to be in the group too. For example, if a door is in a group, that wall should be in the group as well.
Try to avoid hosted elements in your project where possible. For example, pick a toilet from the family library placed on a level instead of a wall hosted one.
Avoid Face-Based Families Inside Groups
Face-Base Families behave strangely inside groups. For example, if you offset a whole group, everything moves except the face-based families. Best practice is to avoid them completely.