How do you mark a corner safely as lead rider.

[wiltshire builders]

The last thing I'd want on any ride I'm on ... leading or otherwise is to have riders determined to charge back to the front of the ride. Can be totally disconcerting to less experienced riders who are not used to others' riding styles.

But that's the whole point of the marker system. The quicker riders can have a blast without leaving the slower riders behind.
As long as everyone uses common sense it's fine.