Depends on the character. But, generally speaking, anything close or above 10k is considered good. Now again, also depends on the duration of the game.
You can spam your shield in front of enemy spawn and get 50k of damage blocked. Useful? Don’t think so.
Fuck the statistics, look at the game: did you shields blocked some important damage? Did enemies break your shield before your cd resets? Did u and your team get shattered by a reinhardt?
These are the kind of questions that matter