When I first was teaching myself on demo for 2 years I stuck with USD/JPY only for the first year. After that I started understanding the movement of that particular pair and slowly started learning the other pairs. Definitely think it’s easier to focus on a few and slowly work your way up when you’re more comfortable. Now I look at 10-11 pairs but they’re literally all tied in.
For example, the pairs I look at are GBP/USD, EUR/USD, AUD/USD, USD/JPY, USD/CAD, GBP/JPY, EUR/JPY, AUD/CAD, AUD/JPY, EUR/GBP. I’ve become accustomed to looking at these guys and understanding what’s going on (in a sense - markets are always moving). It took me 2 years to get comfortable with these pairs altogether and I’m still just a noob imo.