Is there a limit on structures for your settlement?

Well, yes - of course there is. You can only have as many structures as you have slots of land to put them on.
But that’s not what I’m asking. I’m curious if there’s a limit on the number of times you can build an individual structure. Some - like the Brahmin Ranch or the Leader’s Office - clearly state that you can only have a single one of them, but what about structures like the Maintenence Shack?
The downloadable Settlement Sheet has 5 boxes for those, but nothing in the rules says you can’t have more than that.
So the question is: Can I build more than the number of checkboxes on the Settlement Sheet for structures that don’t have a hard limit set in the rules?

Unless stated, there is no limit. The 5 boxes were just a good amount in the space available but are not a limit.