One toughness can be problematic against cards like Orcish Bowmasters, Fire Wrenn and Six, etc., but this is what were working with in Modern
At this point, Up the Beanstalk has been clearly cemented as a best-in-class source of card advantage for slower decks
Carrionettes ability is clunky and certainly not mana efficient, but once its in your graveyard you can keep players on their toes, worried about tapping down their mana too far or else Carrionette can carry off their best creature into the most permanent place in the gameexile
Token engines have a similar use: Cards like Ophiomancer, Sedgemoor Witch, and Bitterblossom produce consistent streams of sacrifice fodder to pour into your outlets
A5: Sample time: 7-10 days, production lead time is usually about 3-4 weeks
It also only takes a turn to get to the ultimate, which can easily end a game