A reoccurring issue I see in all skill brackets is people not effectively using the courier. Now, ignoring the classic case of a courier steal when your pos 5 needs a wand recipe after mid already called the courier for crucial regen, there are some basics that help A LOT in getting items out quicker while simultaneously not angering your team mates.

Courier control makes a huge difference for item timings and morale and I never see this being discussed. So for anyone that might benefit from this info by happenstance, here are some of basics.
– Shift Queueing: Like most hero actions, courier actions can also be queued up, which will then be followed after the unit is done with whatever it was busy with. If you see the courier is delivering items to a teammate and you need to use it right after, simply hold shift and click on the delivery arrow. This will tell the courier to go fetch and deliver your items the moment it is done with delivering its current load.
To expand on this, with the latest update there is now an option right above your stash that notifies the courier that it should pick up your items when it’s in the fountain again. Combining this with a shift queue will allow you to tell the courier to pick up your items whiles it’s busy getting another player’s items and deliver them to you right after it completes it’s original delivery without having to return back to the fountain to get your goodies. That’s basically 1 trip with 2 deliveries without disrupting the original players item timings even by 1 second.
– Sending items to team mates: It’s like nails on a chalkboard for me whenever I read someone typing out “RE USE COUR” since there is no reason to do this. Right clicking on the delivery arrow button will bring up a list of heroes whose items are already on the courier. Selecting one of these heroes will tell the courier to deliver to that player as if that player requested it themselves. This means that if you accidentally steal the courier (or when you are just much closer to the courier and it makes sense for it to deliver to you first) then you can simply right click the delivery arrow button and send it back to the original caller.
Again, expanding on above using shift queuing means that you can either tell the courier to deliver your items and immediately deliver the next person’s items when it reaches you, or tell it to deliver to another person and immediately deliver to you when it’s done. All this without interrupting other players while they are fighting/farming.
One caveat is be careful shift queuing the courier to you after a teammate in another lane. People will have the courier go top directly after dropping stuff bot and the courier will walk down the river and get killed.
Simple solution: Add two queued commands, one sending the courier a little back down the lane into a safer “flight corridor”, the second to deliver your items. For example, when your mid-laner is using the courier and you as the safe-laner also got items in it, shift-queue a move command somewhere behind your mid tier 1 followed by the delivery command so the courier doesn’t have to fly all the way through the river.
Also when defending high ground and you need to get secret shop items, you should shift queue a move command along the edge of the map and then queue the secret shop hotkey so that your courier flies out of vision of enemies before and after it pops out of the trees to buy from the secret shop.
