3. Hybrid: We can adopt a hybrid approach. We can move all the users who have a high number of followers to a pull-based model and only push data to those who have a few hundred (or thousand) follows. Another approach could be that the server pushes updates to all the users not more than a certain frequency and letting users with a lot of updates to pull data regularly.
Is there a typo above? Users who have a high number of followees, not followers, should move to a pull-based model.