[Exim] Understanding remote_max_parallel

OK - I'm trying to understand in relation to exim processes.

I'm trying to tume Mailman and Exim to be effecient. I want fast
delivery - but don't want to overload the system. Mailman has a setting
called SMTP_MAX_RCPTS which I think will break up my 20,000 mailing list

into 40 separate 500 message chunks. (Do I want that?)

Anyhow if I have remote_max_parallel = 5 then I guess these 40 chunks
will spawn 5 processes each creating 200 processes? (200 is OK but more
than say 400 would not be)

On the other hand - I'm experimenting with the idea of starting a queue
process every minute. If these messages got queued (using queue_only)
would the still look like 40 messages with 500 recipients - or - would
they look like 20,000 messages?

What I'm trying to understand is if I set:

queue_run_max = 20
remote_max_parallel = 10

Then - at one minute intervals a new queue process starts forking 10
delivery processes each eventually getting up to 200 processes after 20
minutes. Do I understand that right?

Additionally - I'm setting:
queue_only_load = 2
deliver_queue_load_max = 15

With the idea that it will back down if the load goes too high.

I'm just trying to tune this out right and was wondering if I'm
understanding it. Suggested settings are welcome.