I see players shift-click move their units back and forth all the time in replays online. Why do they do that? Wouldn't a hold position command achieve the same thing?
A unit moving back-and-forth is can be harder for enemy units to kill (especially with melee units).
A common example of this is in PvZ when Protoss sends a Probe to try and block Zerg's Hatchery. If the Probe was stationary, it would be a lot easy/quick to kill it; for this reason, Protoss players shift-click and move their Probe all around the Hatchery location to stay alive as long as possible, thereby delaying Zerg's Hatchery.
The shift-move, or the "queue" command, can have different meanings.
- To scout different locations around the map, so the scouting unit checks out more places and dont go somewhere in a straight line.
- To scout around your own or the enemy base.
- To block off the enemy trying to expand or similar buildings.
- To focus fire a group of units, by killing them one by one. Example: TvZ Shift-attacking Collosi with Vikings has a better outcome than just attack moving into them. It saves you time, and enables you to focus on the other units with your other troops.
- To scout attack, and clean up Pylon, Overlords and such.
shift clicking your units around lets the unit move while you go back to your base and keep your macro up and you don't have to worry your units getting surrounded and dead
this is crucial during early game harass/scout to keep the harassing/scouting unit alive