Christy-Lyn’s Sailing on a Lake has been my favorite warm-up for several months. It has triads in alternating hands, and it gives you time to place one hand while playing the other. I wanted a similar warm-up exercise for four fingers.
Carol Kappus talked about warm-ups in her “Magic Hands, Part 2, The Chords” video. The last chord shape she mentioned is 7th chords. I tried some 7th chords, alternating hands, with some common chord progressions. The one below is similar to the chord progression in Pachelbel’s Canon in D, but transposed to C. These 7th chords also work for many other chord progressions, including the one that Christy-Lyn used for Sailing on a Lake.
It’s easy to memorize, and you don’t really need to write it out. I’m just attaching a MuseScore screen shot to communicate the concept. Lots of possibilities for variations.