For me it was a DIY 100 that I did today.
I had hoped to attempt an SR series this year. I got my first ever 300 in, after which I decided 300 was enough and I no longer had a desire to go any further. But within a week I was thinking maybe a 400 would be doable. Sadly my disorganisation meant I missed the cutoff for Severn Across, and I DNS-ed Asparagus and Strawberries because of bike fit issues that came to light during the Stonehenge 200. Not sure what I'd tweaked but whatever it was made every part of me that was in contact with the bike hurt.
Then before I had chance to ride a 400 I broke my road bike, and life intruded to the point that buying another one got put on hold for a while. So having realised an SR series wasn't going to happen I figured I'd aim at Randonneur 1000, and as of yesterday I had the 100, 200, 300 and 300km of additional rides. Which left a DIY 100 as a last-minute completion to R1000.
The route was one I've ridden before and a variation of a route I've ridden more times than I care to count. Basically I picked a cafe ~30 miles away, cycled there, had a coffee and a cake, and cycled home again. The views along the way range from suburban sprawl to really very pretty. I skirted around Windsor and past Runnymede. Some day I need to take a gentle MTB ride along the Thames as far as Windsor, it's beautiful. But today's ride was more about ticking the box than stopping to take in the views, so basically I just kept moving.