Quickswitch

Quickswitching refers to the strategy in increasing firerate and elimination of shooting speed penalty by switching in certain patterns. Quickswitching on mobile is an extremely rare find. Because of this, flick shots are not very commonly seen on mobile, although if you are good enough you can flick it then use another finger to select another weapon.

One weapon
After firing a weapon, switch to any other (to to melee, or throwables), then back. Result would be your survivr still holding same weapon but being able to move at full speed.

For weapons such as Mosin-Nagant, SV-98 and AWM-S, quickswitch is essential to be competitive; it both increases both firerate and eliminates speed penalty.

For weapons such as Saiga-12, Model 94, USAS, Super 90, etc., quickswitching would decrease firerate; user would have to choose between getting max DPS or eliminating speed penalty.

Assault rifles and LMGs benefit the least from using quickswitch.

Two weapon combo
First weapon fired, switched to second, second fired, switched back to first, 1 second cooldown. The most iconic combination is Mosin + M870.

Double pump nerf
Since version 0.6.0 (sep. 7, 2018), switching from pump shotgun (M870, SPAS-12) to another pump shotgun triggers switch cooldown; thus is no longer possible to fire two in quick succession. The only effect left is elimination of speed penalty.