I think it all depends on your tank decor & filters...& debris. You want good flow toward the intakes however that happens...sometimes minor adjustmests can make a big difference, sometimes not. Especially in planted tanks, I want sponges over the intakes. Even if it slows the flow it keeps "big stuff" out of the filter (any kind) & reduces cleaning.
1 thing I will mention is if you want to help to remove duckweed, you don't want sponges on the intakes...& need to plan to clean filters a lot more often. Try as I might, I have duckweed in 2 tanks but not in 2, your mileage may vary