Small obstacles and wildlife will block all damage from a monsters skill. In this example some dead wildlife is grabbed instead of me.
The only time you should really be using jetpack in combat is to 1) Make distance or 2) Dodge a large skill from the monster. Lava Bomb is one of Behemoth’s big skills and thus you should attempt to dodge it when you have jetpack up.
Watching the monsters animations will allow you to understand the situation and what your reaction should be. Seeing the monster was about to use tounge grab I walked behind the wall so he’d lack LoS on me if I hadn’t positioned myself close to this wall I would have had to use jetpack to break LoS.
Grouping up will bring your team down quickly. With some skills doing 1/3->1/2 of a hunters HP bar it’s devastating enough if one hunter gets hit. If multiple hunters get hit it’s generally a fight lost.
Sticking on the high ground will slow the monster time. A slowed monster will give you more time for your jetpack to recharge. The longer your jetpack recharges the more dodges you get. The more dodges you get the easier it’ll be to stay alive.