If I need to make a connection only for some time, is it allowed to screw the bolts till the end and not to shear them off, so that I can easily unscrew the bolts when I need to disconnect?


No, it is not recommended to do so. It is carefully calculated that a reliable connection is ensured after the shear off the bolt because it guarantees the necessary force. If the head was sheared off, it is not possible to use the connector one more time.