How to optimally make API requests in Bitrix

Has anyone had experience? Please share. I'm working with their CRM, trying to export all data about our leads to my database via their API. This will be a daily procedure. But so far it's a mess - for a batch of 50 leads, I need to make 151 = 1 + 50*3 requests. Considering they have a limit of 1 request per 0.7 seconds, and there are 30,000 leads, I'm feeling hopeless. Their documentation (as well as the data structure) for the API leaves much to be desired. How did you deal with this? Please share your experience!! I'm connecting via webhooks.