Before you set out
Three days: use one base
Start in Ponta Delgada. Pick the clearer day for Sete Cidades and use a separate day for Furnas village and one managed bath. Keep the third day for the city, the north coast or Lagoa do Fogo if access and visibility cooperate.
Five days: add a night in the east if it helps
Use the first part of the stay for the west and central highlands, then move to Furnas for the valley and a slower evening. Add Ribeira Grande on a separate north-coast outing. Leave the final morning close to your airport transfer, not committed to a remote trail.
Change the order, not the pace
On a low-cloud day, trade a crater panorama for the city or a confirmed garden visit. Check trail alerts, access and tickets again before you leave. If a site closes, skip it rather than filling the day with an improvised drive.