What determines the time a message is included in the IOTA Tangle?

Question

I have a Hornet node connected to the IOTA network. In turn, from my own node I'm sending different messages over the Streams protocol.

The propagation times I get give me no clue about why some messages are validated in less time than others.

Here are my doubts:

1. Does it affect the number of peers connected to my Hornet node?
2. Does it affect the size of the message payload?
3. Does it have something to do with the current state of the network at that moment?

Thanks in advance.