Most people in Randonneuring do one Super Randonneur series (a 200K, a 300K, a 400K, and a 600K), and maybe one or two longer events (1000K and/or 1200K) each year. They might throw in an extra 200K or 300K if they feel like it.

Added up, that's only 5-8 events a year.

While each of the events is time consuming, the training isn't really any more time consuming than racing. Most of us "train" by commuting to work, going on evening rides when the weather is nice, and doing some longer rides on the weekends at a nice comfortable pace, with the distance of those rides, and the frequency of those rides, being up to us. If we want to cut it short, we do ... if we want to keep riding all day, we do. So ... there's a lot less pressure than racing, and not really much more of a time commitment than racing (perhaps less).