My experience is the same. Sometimes the spline end point just refuses to be placed. The usual trick is to place it somewhere further away where it does stick, then move it back into place where it was supposed to be. I haven't associated the problem with textures, but perhaps I didn't look closely enough. It is not a problem with other splines points too close by, because when it is moved into its correct position there is nothing that it tries to join to.
Using Shift to force it to place itself is a cool trick.
Here's another trick I haven't seen mentioned:
When doing straight splines like fences and walls, it's actually quicker and easier to allow the corners to join up into one long curved spline, and then go back and disconnect them later. This ensures that the corners points are exactly placed over each other. To move them, click and move to force them to reconnect, move the connected point to the new location, then unjoin.
