A few years back I was single and on Hinge a fair amount. If you used Hinge back then, you'll remember some key differences between the platform and other dating apps: 1) when you "like"'d someone, you'd have to comment on a specific part of their profile (a photo, a prompt answer, etc), 2) these likes showed up in their inbox, independent of whether they liked you or not (as in, you didn't have to like each other mutually; the other end decided whether to reply or ignore after delivery), and 3) there was limit per day, you could like/message 8 profiles per day, no more. On average, swiping through my 8 per day, I'd generally get 1-2 new replies, which turned roughly into 3-4 first dates per month.
One of the key elements is that the inbox was time-ordered: the most recent like you received was at the top. There was discussion on the Hinge subreddit about how girls would typically only click through the top few items in their inbox daily, and if you were lower down, you were doomed to drown under the mountain of new message they're getting on top. So I figured I'd solve for "what is the optimal time of day to be blasting out my likes to ensure I end up higher in the inbox?"
You can probably see where this is going: I requested a GDPR data export, which happened to have all my conversations, time-stamped. Crunching through in Python there was something in the data I didn't really expect.. a disproportionate number of first-replies (replies to my initial like/message, that is) were around the 2-3pm bucket. Not what I would've expected (don't these people work?) but fair enough, I started doing all my swiping in those hours instead of in the evening as I usually did.
And it worked. Good god did it work. I consistently started getting replies to 70-80% of my initial messages (from the ~10% before). I was drowning in conversations to the point where I wouldn't swipe at all for days for fear of yet another conversation to manage. Within a few months I ended up meeting my current girlfriend and haven't been back on since, but it was surprising how well something simple like time-of-day affected my reply rate.