There are two types of linear guides: ball guides and roller guides. Poor installation of linear guides will cause the following consequences.
For roller guide rails: If the installation is poor, you should look at the degree of poor installation. If the installation parallelism error is within 1mm, mature manufacturers (such as Nadella) have floating rollers and other products that can solve it, and it will not affect the use. But if you consider using roller guides to avoid installation errors, it means that the accuracy you need is not particularly high.
For ball guide rails: Poor installation will directly lead to a significant decrease in service life, because the ball guide rails are manufactured for high precision, so the requirements for the mounting surface are extremely high. In addition, poor installation may cause jitter during operation, and even the slider cannot move. If high precision is not required, it is recommended not to choose ball guide rails.