Very much opposite xp from mlmooy's description when I went this year cny, 3days b4 to 10 days after cny day1.
Everywhere was bustling until late every night. On eve, reach taichung 5pm, the busy night market was dead, all closed, tot we went wrong place. Check-in, shower and watch tv, 8pm came down for dinner, wtf the whole town was celebrating loud and ask shops opened again. We learned that shop keepers closed at 4 and came back 7pm to open shop till morning.
Elsewhere in the whole island on the east coast, mountains and attractions, many locals, little Chinese tourists.