There are a few usage limits for email campaigns.
Limit to the number of Email campaigns you can have active at one time: 8
Limit to the number of desktop product widgets per active email campaign: 2
Limit to the number of mobile product widgets per active email campaign: 2
Limit to the number of image widgets per email campaign: 2
Limit to the number of HTML widgets per email campaign: 2
Limit to the number of served campaigns per email: 2
Limit to the number of served recipients per LimeSpot subscriber per minute: 200
If any of these limitations are exceeded, the elements will still render, but render with a latency as they will have a lower sever priority.