Tactics on how to adc in temfights (searching for ones)

I usually play Vayne (kog, tris)

In some of the games focusing and kiting the tank that is infront of me just isn't enough, the enemy is more fed and deal more dmg, kill our front line (if any) and then me or the melee champs (depends on position)

I have only one trick that I usually do with Vayne -

Let's say the enemies and our formation is like that -

×  ×  ×
  X   X
  M  M
v  m  m

Legend - X - the enemy frontline x - enemy back line M - our frontline m - our back line v - Vayne (me)

few seconds after the fight have started (and most of their hard cc is out) if I'm noticing that their back line getting little spreaded (but still in the back line), like that - x -- x -- x X X Instead of x x x X X I position myself to the left/right of theenemy team, like that -

z - - - × × ×

• • •      X   X
      

• v - M M

• • •      m  m
      

Then when the tank aproaches to me or someone try to focus me I ult and flash to here -

v × × × X X M M m m

Hopefully killing some dps mage or adc (in that stage of the fight the melees are already in) and killing or severely injuring another backline character before dying so my teammates can finish the fight.

It sometimes work and the only thing I know to do beside focusing the one who's in front of me and kiting away..

Do you have more tricks/things I should do?