I use trainerroad plan builder, and shifted the date of my A race up a week (to coincide with my club's race, which is a favorite of mine and I'd love to be in peak form then). Anyhow, as a result the plan builder inserted a week of sweet spot base this week as filler prior to starting the CX specialty plan next week, I'm always ok with more sweet spot, my progression level has gone from 10 in June to 3.7 currently