Once Oberon comes to NA you will do funny damage numbers with the top tier archers (Gil, Tesla, Ishtar). If you use Jarcher at NP2 with BG using plug suit Oberon you still hit 400k+ damage with a level 5 decisive battle MC.
On to your initial question though, in a scenario where 3 turn actually matters (ie lotto), on 90+ nodes wave 2 has 140-160k hp mobs, while wave 3 has 170-210k ho mobs. If the HP is very high you should get bonus damage one way or another. So if you do 160k you might fall short on some nodes.
For 90 nodes though wave 2 has a tank mob with 70k-110k HP, while wave 3 has between 120-140k HP, so you are good on that front.