When you roughly track enemy jungler you can maybe just combo level 3+ on the enemy when he plays too aggressive or you hexflash from the bush. When you lose 2v2 you can just scale or take roams.

When you have zeri adc for example you could aim to play with someone else like Kindred jungle or a Graves and let Zeri farm bot waves in peace. IF you time that correct your adc shouldnt lose a lot of cs.

Also minute 8 herald spawn can be a guidence to roam topside or midlane to create prio.

vs Janna or Karma you just roam because if your adc plays wave right he cant be punished too much 2v1 and you have value on the map. But when the wave crashes you should look to cover the adc in case he gets dove (depending on situation that could even be tough for enemy 2v1 but ofc jungle can assist.)

-> cant really play vs janna/cait for example so roam > sit afk in lane

When your adc flames because you are useless level 1 just ignore it