How Do You Practice a Deck in Master Duel?

Curious what everyone does when they're learning a new deck in Master Duel. Is there a specific CPU opponent you pick depending on what you're practicing?

Like if I just want to run through my full combo uninterrupted, is there a certain CPU that's best for that? And on the flip side, when I want to actually test my disruptions and learn when to use them, is there a different CPU that fights back enough to make it worth doing?

I've noticed Moha - Master Duel runs his easy guide and decklist videos against the Danger! CPU, though I can't tell which specific duel in that gate he's picking. Is that the community go-to, or do you all have better setups?

Lastly, is there any way to truly practice a specific combo line? Say I see a "Branded Opening" combo I want to learn. Can I somehow set up my opening hand to have Branded Opening in it so I can drill that sequence, or are you always stuck with real match rules against the CPU with no way to filter your starting hand?