When to 3-bet and when to just call???

[IrOnLaW]

Under what circumstances is it more profitable to 3-bet someone as opposed to flat-calling their bet??? The question includes both in position and out of position....
Possible scenarios....

1. KQs in BB, 32/24 raises from button, what's our move...
2. JTs in SB, 18/12 raises from CO.....
3. 78s in BB, 24/17 raises from button.....
4. KJos on button, 32/24 raises from CO.....
5. 88 on button, 32/24 raises from CO.....
6. AQs on CO, 18/12 raises from UTG.....
7. 99 on BB, 24/17 raises from button....
8. 45s on button, 24/17 raises from the CO....

FYI, it is 6-max, and you range from 18/14 to 21/17
100 bb Stakes