How to get all repository in all projects in bitbucket using bitbucket server API?

[AzeemUllah]

What i want to do is calculate mean time to approval. 
Simply put; how much time it takes for one PR to get approved since it was opened. 

Lets say I have 50 projects and in each project has 5 repo. What i am doing right now is:

1. Get list of all projects (1 API call)
2. Get list of all repo in each project (recursive: 50*5 = 250 API calls)
3. Get pull request history for each repo and in each project (recursive: 250)

As you can see there is alot of API calls being made and this will increase my a multiple ratio as repos and projects increases. 

My question is:

1. Is there a way of getting like whole bitbucket pull request history?
2. Is there a way of getting all the repo in all over projects with one call? 
3. Is there a better way of achieving what i want in some other way?