When writing macros that expand into forms that might involve grouping, it is worthwhile spending some time considering what grouping construction to expand into.
For definition style forms, for instance, a define-widget macro that will usually appear as a top-level form, and that several defuns, defstructs, etc., it usually makes sense to use a progn, so that child forms are processed as top-level forms. For iteration forms, an implicit tagbody is more common.
For forms that define a named "chunk" of code, an implicit block is often useful. For instance, while the body of a defun is inside an implicit progn, that implicit progn is within a block sharing the name of the function. That means that return-from can be used to exit from the function. Such a comp