A time dimension cannot be used twice as a group by in GUI

It seems that a time dimension cannot be used twice in the GUI of custom questions. For example here I'd like to do a Day Of Week / Hour of Day matrix which is a pretty common activity report.
The GUI prevents me from doing just that . The only work around is to join twice on the same table which is overkill and missleading.

Hi @gchev
Yes, it's something we're currently working on trying to address:
https://github.com/metabase/metabase/issues/4726 - upvote by clicking :+1: on the first post