Placing a pole first isn't always a solution.
Here's one example:
* build a row of storage containers side-by-side
* select a conveyer type, aim into the output port of the container, and double-click
Result: a super short section of belt that lets you see what's in the container. Unless you hit the "Floor is not flat" issue, in which case you can't place the belt. You can place the pole manually, but because of how close to the container it needs to be, you can't hook to it; it's not possible to find an aim point that hits the 'back' side of the post.
If there are other known work-arounds I'd like to here about it.