Depends on your strategy.
You could do a breakfast breakout strategy for under an hour a day. There’s quite a few variations on this.
There’s a 1 hour breakout strategy in a thread somewhere (here - London Breakout Strategy - 1H Timeframe Modified) that could be done in as little as 5-10 minutes a day. Not saying it’s profitable though, I’ve not tested that over a long period of time.