I’m using the zones as defined by Dr Seiler Polarized Training Discussion (Fast Talk podcast & Flo Cycling podcast) - #84 by bbarrera
The intent as I’ve gathered from Seiler’s research and statements is to do 2 (maybe 3) very high quality sessions a week above your lactate threshold (ftp), and the rest in zone1.
There is definitely a role for sweet spot, in particular during base, as studies have shown it to be effective.