How do I set the total submissions limit when I create a node?
Go to the Webform's settings
(/admin/structure/webform/manage/contact/settings) 
Scroll to 'Submission Limits' 
Set 'Total submissions limit per entity' or 'Per
user submission limit per entity'


I think the labeling and additional help text could help better define this features.  Feel free to create a ticket in the Webform module's issue queue