Just like the past 2 years, it takes 20 attribute progress bars or 'cap breakers' to unlock all your attributes and reach the max OVR. Unlike the past 2 years, however, the max OVR you can reach through these cap breakers in 2K20 is 95 rather than 99 - so there are 20 cap breakers to go up 10 OVRs rather than 14 meaning that, on average, it is going to take filling the bar twice to advance, however this doesn't necessarily mean it will be 2 every time, it may be 3 one time and then just 1 later on.
Once you fill the cap, you will receive either 5, 6 or 7 new upgrades to spend. Guards tend to have more total attributes so will receive 6 or 7 most of the time while bigs will see 6 most of the time and maybe occasionally 5.
See the MyPoints Required page to learn how many mypoints each cap breaker takes.
I have grinded two players to 95 so far (an Offensive Threat and a Glass-Cleaning Lockdown) and both followed the below table so I feel it may be likely that 2K have gone back to the format in 18 where every build had the same cap breakers between OVRs. I haven't confirmed this yet so for now, use the table as a rough guideline.
|OVR||Number of cap breakers|