You can boost FTP up in two ways:
1) Push it up.
2) Pull it up.
#1 is usually less taxing and can be done more regularly.
#2 is more draining and it takes the body longer to recover so you can do them less often.
So usually, you can do #1's on a much more regular basis (even everyday if you do other things correctly). Thus, they might do less per interval but the quantity of them helps more than doing less of something that does more.
You're right. He's preaching SST below threshhold.