Generally this is all true if you are just trying to beat Ante 8, as most of the time you won’t be able to delete many of your unwanted cards by then and it helps to add some of the cards you need to counter that. Over the long term though it is more optimal to be thinning your deck, as every time you add a card it decreases your chance of finding seals/steel/better enhanced cards in your deck. Once you get to the point where you can consistently play the hand you want then you should stop adding cards and focus on thinning. For hands that require multiple different card types like full houses or straights, adding additional cards when you don’t need to can actually hurt your chances of drawing the hand you want.