But when you "spontaneously" send that order in any mean-reversion strategy, it will be a limit order, not a market order. It will still wait to be filled, and

But when you "spontaneously" send that order in any mean-reversion strategy, it will be a limit order, not a market order. It will still wait to be filled, and may not be filled. Maybe you sit at the bid, maybe the midpoint, maybe hit the ask, but it for sure won't be a market order.