Just finished Chrono Trigger!
So it turns out the tragic thing that happens to Frog is his past, rather than something in the story. And yet SOMEONE does actually "die". When Janus gave me that warning, I thought Frog's death was soon. So Crono dying instead came as a big surprise.
My final save time was just under 22 hours, so including the final boss and ending perhaps just under 23 hours total. Speaking of, damn that final boss was long and epic. Two long phases, with a 10-ish phase penultimate boss (most being very short mind) and 3 phase antepenultimate boss. My final team was Ayla, Frog, Crono, at levels 46-47 - Falcon Hit is pretty fantastic for enemies in a line, Confuse and Luminare are just generally good from Crono, and I had the Swallow so he was super fast and powerful. Frog mostly provided great Dual Techs with Drop Kick being my most used, but Spire and Slurp Kiss saw a decent amount of use. Their triple tech, 3D attack, was honestly not that useful as Confuse from Crono + Drop Kick from Frog/Ayla deals more damage, and doesn't slow Crono down in having to wait for their ATB to fill up. I did switch party members around a lot, I did manage to learn all the single techs on everyone (some inside the Black Omen, even right up to near the final bosses), but probably missed some dual techs and most triple techs from not using the right parties after all the single techs were learned... oh well.
Overall I really enjoyed the game. I can see why it's so beloved of SNES games. It has a solid plot, great gameplay, lots of customisation. I know there are many endings you can possibly get, and there were several sidequests I didn't do, but maybe another time.