I take recovery weeks very easy and by feel. And I do FTP test(if neccessary) mid recovery week, when I feel good. Riding z1 and z2 for entire week and then jumping to ftp test doesnt work for me either.
For rest weeks I really go by how I feel and how deep of a hole I dug for myself. In many cases I feel tired mon-wed and then start feeling like I need a real workout and may slip 1 hard short session around Thursday or Friday and for me it has worked but you really need to be in tune with your body. When in doubt I keep all the workouts during rhe recovery week true recovery
Some tempo closer the end of the week (like 2x30@85%) works for me. I also have a problem that my legs works way better after some sort of intensity closer to new block of training.