Getting a sponsorship will require one to achieve Tracking rating based on the latest 2 reviews. Although some office might require higher rating above Tracking.
The rating system are normalized, meaning your performance is being compared to the performance of your cohort in the Firm. With the Firm filled with highly-driven professionals, these could indeed prove challenging at times for some, although for tracking, it should be very doable.
Most of the people who stayed typically gets an opportunity to propose for and receive the scholarship (since getting Tracking means you are not counseled to leave in this case), although it is indeed to offer to jump straight to Associate for high performing ones are quite enticing and preferred by the Firm.
One can apply for the funding once yo have ticked all the boxes, hence you have somewhat of a control in getting it.
Hope it helps.