What is the typical amount of ui/ux designers in a company and day to day activities?

Anyone know how many ui/ux designers are usually in a company? Specifically a mid size company and how do they work together? If there are multiple ui/ux designers then how is it decided who does what? Do some focus on certain deliverables? Certain pages/sections are done by each designer? Also what is the day to day activities and duties like? Do you create a project for certain clients that the companies work with? How long are these projects typically and do you just move on to the next one once finished? Spend time iterating?