I note on your opening post mention of stock indexes, so I'll assume maybe a handful?It doesn't have to be, you can trade 2 hours a day or 20 hours a day. Entirely up to the trader.
As for Systematic vs Discretionary vs Hybrid. I don't see much difference between them, in that the deciding factors are things like patience and emotional control (how you emotionally handle losses).
My mind had wandered off and was thinking of stocks, so a larger universe, which then brings in issues of too many choices.
Yep, so just a few indexes is probably a good idea.
Do you think perhaps trading discretionally will give you some further new trading ideas for using in the sometime distant future, what do you normally trade?