Yep, all the games have a handful of sections that are somewhat difficult but the Jackal Snipers are pretty consistent with their spawns. If the player can't adapt/learn the spawns, then that's their fault.
Halo 2's problem sections for me were the seemingly infinite spawns of Jackal Snipers by the Gauss Warthog's first appearance on Metropolis, Heretic/Regret boss fights and the intro to Gravemind (the one where you start with the Brutes). Rest of the game is fine in my opinion.
They are random at the beginning of Regret but the large room with the giant hologram is not better, it's the only place I don't like in the game because there is a lot of places where Jackals can be, like the beginning you can perfectly see one but not another who see you in turn because you check that corner right there. I'm often unlucky in that room and this where I lose the Marines too.
The Heretic Leader fight can be ended easily by gathering and holding a Fuel Rod Gun from the previous mission until the fight.
The pressure from honor guards can be lowered by boarding the last gondola and taking the Fuel Rod Gun from the 2 Grunts, they must be scared and not killed so they drop a FRG with 20 shots. It's not really needed since Plasma Grenades can deal with Elites but it's good if one is unavoidable and must be killed at the moment.
Never had any problem with Gravemind except for the prison area and the very end of the mission, the Brute Shot is a good weapon to deal with pretty much everything in the mission, good weapons are everywhere too.