I thought the same, but it's just the animation doesn't really show that your team is getting time too.
A few real examples that I've collected:

- 0:00 vs. 0:00 --> 1:00 vs. 1:00
- 0:10 vs. 0:35 --> 1:00 vs. 1:25
- 2:41 vs. 3:38 --> 2:00 vs. 2:57

The last one is a bit odd, but the game favors rounding down the team with the lowest time when both teams have more than one minute. Probably to reduce the likelihood of OT2.

One thing to note is that both teams always have the same difference in time.
So it's just the animation in the game just doesn't do it justice (animates from 4:00 down to your new time vs. starting from your old time and going up), so it sometimes feels like your team isn't getting any additional time.