In wrestling that's how they teach it and execute the technique, yes. In MMA they often prefer the head on the outside. Sometimes MMA fighters will specify it as an inside/outside but many won't distinguish the head positioning. Usually though if it isn't inside then it tends to be specified when referencing one. You're still attacking a single leg with a single leg TD and a high-c TD, and the grip level can be the same, and the head positioning can be the same as well. In fact, you'll see a lot of MMA wrestlers shooting with their head to the outside on their singles and double legs (and there are a couple different reasons for why this is).
If you shoot and your knee doesn't touch the ground, it's still a shot for a takedown whether you do or don't touch down with the knee. As long as your head isn't down facing parallel to the floor/mat and in tight to their body then it's position, inside or outside, is not important. Most wrestling coaches will always tell you to shoot single legs on the inside because that's how everyone learns it in wrestling and they don't want you to leave space by having your head on the outside when teaching the technique.
