The way fascat describes sst is almost like "ride lots". Almost all of my rides (except recovery rides) at this time of year fall into one of the SST workouts, although I don't have a power meter to verify my normalized power is in the right range. I guess when a lot of people go out to "ride lots" they are riding at more like tempo power for longer, rather than sweet spot. My favorite ride at this time of year is to get into a sweet spot heart rate on the fixie and hold it for 60-90 minutes. I imagine my power would be lower at the end of the 90 min since I hold roughly the same HR.