Yes. Currently her ult gives 300 armor over its duration, but is capped at 150 total over their health.

This means if you use it out of combat to just generate armor for your team, you’re effectively only getting half of what its potential if you had it running during combat. Also the speed boost Brigitte gains is very useful for her to get important melee hits in and stunning key targets.

That said you don’t really want to pop it in the same way that Lucio or Zen use their ults. For those heroes, its often about using it in reaction to big incoming damage to save allies nearby. Brigitte’s is more proactive, as its often better to use it a little big ahead of a big fight so it has some time to stack up a little bit.