How many things should you plan in one day?
Build a day around usable time, real travel gaps and the stops that matter most.
Start with available time, not a target number
There is no useful universal number of sights per day. Arrival, check-in, meals, travel and departure all take time. Write down your first realistic start and your last fixed commitment before adding attractions.
Anchor the day, then check the gaps
Choose the activity you most want to keep. Place any fixed booking at its actual time, including its check-in requirement. Work out the door-to-door journey on either side: walking to a station, waiting, changing transport and finding the entrance all count. Verify opening times and admission rules with the venue before booking.
Separate essentials from optional stops
Add nearby optional stops only after the essential activity and meals fit. A map pin nearby does not tell you how long a visit or queue will take. If everything depends on leaving each stop exactly on time, remove something rather than making the day faster.
Give the day an easy alternative
Decide what you would skip if lunch runs late or you feel tired. Keep the replacement near the part of town you are already in. In the Faro sample, the evening allows time to return and rest after the boat trip rather than adding another timed activity.