I used to think that I should always use focus-fire when controlling a bunch of units – i.e. tell them all to target the same enemy, in order to bring it down quickly.
However, I saw some replays from top players and it seems that they don't always focus their units fire. I've been thinking about it and it seems that focus-fire does have some disadvantages:
- It requires a lot of attention (micro) which I could have invested elsewhere, especially for longer battles.
- The AI might not be able to respond smartly when the focused unit is moving backward but other enemy units stay put.
- It might lead to "overkill" – too much damage wasted on a unit which requires less damage to be destroyed.
But it still seems to be beneficial overall… so when should I use focus-fire and when should I just let my units duke it out? Let's assume there's no specific unit I just have to take down (e.g. a detector), in which case it's obvious I should focus it.
Best Answer
Focus fire is critical for sniping injured units and for taking down important or high DPS units like void rays, ghosts, brood lords, immortals etc...
But beyond that, it actually worse to focus fire units. Using this awesome map, I have actually tested micro battles with and without focus fire. I have found that 9/10 times any group of units I micro to focus fire just flat out lose to non-micro'd units.
There are two problems with naive use of focus fire. 1) Targeting one unit will most likely cause you to over-kill the unit, which is a waste when you could be shooting at another target. and 2) If your unit is not in perfect range of the target, the unit will bumble around until they are, which means instead of attacking, they are bumbling around.