To chain three calls, the client will send three messages, yes. (At least when using the WebSocket transport. With the HTTP batch transport, the entire batch is concatenated into one HTTP request body.)
But the client can send all three messages back-to-back without waiting for any replies from the server. In terms of network communications, it's effectively the same as sending one message.
But the client can send all three messages back-to-back without waiting for any replies from the server. In terms of network communications, it's effectively the same as sending one message.