From what I know (I had 1 listing with 4k views and 200 messages once)
It depends a lot on
- the number of views you have, this of course depends on your photos, price, title, but more views you get, more your listing is up, so you get more views etc..
- the number of answers you receive, your listing will be judged as attractive so it will be up and get more views so more messages etc (depends as well on your offer and description of course)
- how fast you reply to first answers, probably few people know that but it is a very important criteria, try to answer asap when you receive a message about the marketplace and you will notice that you receive more answers after that (and opposite if you take time to answer)
Also you should know that you can put your listing up once every 7 days, it will help a lot specially if the listing has good stats, but if the start is bad it is better to delete the listing and post again and always try new things when it doesn't work (change title/photos/description) till you find the good formula.
Good luck