Three days in Paris becomes easier when each day has a geographic focus instead of a long list scattered across the city.
Day 1: central Seine and Louvre area
Group the Louvre, Tuileries, central river walks and nearby historic streets so most of the day can be done on foot.
Day 2: Eiffel Tower and western Paris
Use the Eiffel Tower area as the anchor and add nearby neighborhoods or river time without repeatedly crossing back east.
Day 3: Montmartre and one chosen neighborhood
Pair Montmartre with a second area that fits your interests rather than trying to cover several distant districts.
Keep one flexible block
Museum queues, weather and spontaneous stops can shift the schedule. Leaving a few hours open makes a short trip more resilient.