Yes... If they aren't confident in the theirs as they stand to do what they should be doing (ie: the higher levels 3 and 4 to be short periods of 2-4 weeks to bring down numbers, and the lower tiers the "maintenance" state for the longer term) they have the freedom to tweak them. But don't claim the scientific high ground by having measurable targets and models and everything for moving between tiers, to just ignore them and insist "the only way is up".
I do have that slight concern on the vaccine too anon. It's great news and does sound promising, but yes, if that can be rolled out by December/ Jan into the spring, AND furlough is guaranteed til March, there's really no motivation to even try to "live with" the virus and try all the balancing of risk vs benefit. Hopefully then they can ditch all the tiers, though, and move into phase 4 of "old normal"... 