I've seen requests for hiding activities from the feed (zwift for instance, and I can see why). I have a similar-ish feature idea. I know a lot of people who do multiple activities in a day (I'm guilty of this), and as such, they can clutter the feed of others.
My feature suggestion:
If an athlete performs an activity on a day, have that show in the feed as normal, butif the same athlete then uploads more activities, group them into a single section that can expand/collapse (+/-) so that others may see just a 'summary card' of the activities rather than all of the activities that person did in a given day (or, expand to see them all). It would be an accordion like feature, and in the settings, you could set default to expanded or collapsed, so you could choose how those show up.