Trying to synthesise previous posts.
Semiretirement seem to be w*rk. Only it is work done by someone who doesn't need to w*rk either because already (or very close to) FI or at least blessed with a pretty good GTH fund.
Consequently there is less financial and time demand than earlier w*rk.
I personally would want that phase to be as short as possible. I'd rather choose to work for example 1 more year at 100% rather than 3 more years at 33%.
Unless there is a pretty good reason to gradually phase work out rather than abruptly? (I am thinking of lifestyle adaptation maybe).