@OP
Take this with a grain of salt.
This is just my opinion, and due to the bathtub clear water, and severely pressured lakes I fish. "I can see 12 feet down on some days, a Quagga "Spelling?" mussel lake".
It depends on the lakes you fish, time of year, how much pressure and technique you are using. I fish a lot of slow bottom baits, with these, the fish have more time to look closely at the presentation. So a leader is a must. I won't get a single bite without one. And this may be how fast or slow the worm falls
If fishing top water, a mono leader helps with shock and to keep the hooks from tangling on walking baits. On crank baits i rarely use a leader, but will use a moderate action rod.
If fishing thick brush, or cloudy water I don't feel the need for a leader.
This is just my experience, so don't take it as Gospel.
Spider.