There are 2 general cases when athletes pass on jumps:
- The height is too low
- They want to go up in the standings
Usually when an athlete starts jumping, they don't pass to preserve energy. The jumps start at a lower height and incrementally get higher. So a better jumper might skip the first few jumps, while the others attempt them. Once the jumper starts jumping, they won't skip to preserve energy. So they do care about energy preservation, but that happens when the height is too low.
Sometimes a high caliber jumper might go for a low height jump and then skip a few till their usual starting height, just to get the jitters out (this scenario might be more relevant to pole vault than high jump).
Another reason to skip is to catch up to the jumpers that already cleared the height, this usually only happens towards the end of the competition. This is because of the tie breaking rules, or the countback. If jumpers are tied on a height, the advantage goes to the person that took the least amount of tries to clear that height. If still tied, advantage goes to the person with fewest misses throughout the competition. To explain this, let's go over an example:
There are 4 jumpers left. 2 jumpers just cleared 2.00 meters and haven't missed on any jumps so far. Third jumper cleared 2.00 meters on their 3rd attempt, and they had no prior misses before this height. You've had 2 misses on 2.00 meters, and 2 more on previous heights. So if you make the 2.00 meters jump on your third and last try, you remain 4th due to countback. The first 2 jumpers will be tied for first, the third jumper is in third position, and you in fourth.
But 2.00 meters is really close to everyone's personal best here, and a 2.02 meters jump might win the competition.
In this case, it'd be advantageous for you to skip 2.00 meters, and do your next jump at 2.02 meters.
If you make 2.02 meters, and everyone else misses out, you win the competition. Or if anyone misses their first try on 2.02 meters, you'll move ahead of them.
The skip has little downside. Had you not passed, regardless of missing or passing your third try on 2.00 meters, you would've still been in the 4th position. The only upside of not passing is that if you make the jump, you get a new set of 3 jumps. Since 2.00 meters is close to your PB, you might as well move up and try clutch the next jump.
But in another situation if 2.00 meters is well within your and other aesthetes' capabilities, you may not risk the skip and instead go for the easy jump and ensure you remain in the competition.
So skipping towards the end is strategic to push for a better standing, specially if a qualification, or a medal/podium spot is at stake.