From my own experience the 2 large turrets at the end of the stage 2 don’t even shoot at the convoys.
Also if you are not staying close to the convoys and go too far ahead then that’s not really good practice anyway.
The small turrets aren’t really priority until you get to the ones at the end on the hovering disc. Basically priority in stage 2 is large turrets and any pirots shooting at the convoy then near the end the hover turrets then the last 2 at the end which only fire at you and don’t go too far ahead. Turret respawn is something like 4 minutes so if you do that then its not a problem…
Hey, just sayin’ 
From my own experience the 2 large turrets at the end of the stage 2 don’t even shoot at the convoys.
Also if you are not staying close to the convoys and go too far ahead then that’s not really good practice anyway.
The small turrets aren’t really priority until you get to the ones at the end on the hovering disc. Basically priority in stage 2 is large turrets and any pirots shooting at the convoy then near the end the hover turrets then the last 2 at the end which only fire at you and don’t go too far ahead. Turret respawn is something like 4 minutes so if you do that then its not a problem…
Hey, just sayin’ 
It’s not the point about the difficulty, but it’s a feature, that works nowhere else, because it’s not supposed to, so it’s a bug.
It was actually listed as a fixed bug some time ago, but maybe such bug got missed, or it resurfaced again.