Apologies to the OP if I am misunderstanding, I’m maybe confusing their post with the umpteen similar posts, but my reading is they are doing a HV plan but they are substituting a SS Sunday work out with a Z2 ride which when associated with Town Hill an endurance workout which subsequently lowered the level of his future wo’s in the plan. Which they found a bit surprising. AT simply doesn’t handle any unstructured outdoors rides at present and the TR advice I was given was to go to a lower volume plan and treat outside ride as separate to the plan and not try to substitute them into a higher volume plan. To hopefully get AT to calculate in a way that you don’t find surprising. Hopefully PL’s 2 (or whatever they are called) is released soon and AT will be able to calculate in a method that is understandable and let people substitute rides in properly 