Is signal R async in its networking (not in its calls)

Question

We are using signal r to fetch data for 20 tiles.

We call FetchData() on all 20 tiles at the same time, it then fires of a message on signal r to request that data. (each tile has subscribed to get the answers)

We find that each tile will populate its data one at a time, as if the signal r only fetches the next tiles response after the first tile has been completed?

I know this is super high level, but in my mind, it worked like an AJAX request. Where if I fired off 20 requests in a row, they would all randomly return out of order?