B2B lead generation starts with a definition. Which enquiry is worth a sales conversation, and which is not? Write that down so marketing and sales are not counting different things.
Then build the page and the form that collect it, and point the campaign or the search work at that page. A shared inbox with no owner will waste a good page.
Review the leads with the people who follow up. If they would not call them, the definition or the page is wrong.