According to Forecasting: Principles and Practice
Seasonality is always of a fixed and known frequency.
If it is a fixed and known frequency, does that mean every series with monthly or quarterly data can use methods that captures seasonality?
I am asking because I am not sure if I could use SARIMA and Holt-Winters with my monthly data because there seems to be no seasonal pattern based on my ACF plot. But I've seen some papers have D=0 in their SARIMA model.