Axis should definitely be at proper position. Otherwise you will get at least 2 issues.
1. Carriage will be pulled up which will cause stresses on rollers or slides and it will stress your belt
2. The way the carriage will go will change but because carriage itself is fixed then it will change the speed
3D printing is a precise process. Both issues will have impact on printouts and all your printouts will have broken dimension in the axis in which carriage moves.
Have a look on the picture (it is big to show details)
 change are very small.
**fig B** shows a situation where carriage is relatively close to the axis
Then both - the force and the distance change is noticable