When speaking of Bollinger Bands, most of the sources say that the recommended period is 20 days while saying that this could be used on different time frames - for example see the first chart here: https://www.tradingview.com/wiki/Bollinger_Bands_(BB):
Seems like kinda inconsistent advice. Isn't it then actually recommended to use 20 candles (candle being 1, 2, 5, 15 minutes, 1 hour, ... depending on time scale) rather than 20 days? It wouldn't make much sense to use 20 days on 5 minute chart would it? Also tradingview by default uses 20 candles. Just want to confirm on the recommendation.