When Following the books on a shelf tutorial. When I angle the books with the transform operator, they space out and do not rotate together.
Unfortunately, since the tutorial was recorded the Transform operator's behaviour has changed slightly. At the time the tutorial was recorded, rotating using the fixed transform controls did not change the size of the bounding box used to calculate adjacent segments. In recent version, to match the same behaviour in the Segment node, this parameter does change the bounding box so the segments are pushed apart.
To fix this, instead of entering the angle in the Fixed Rotation settings, set identical values in the minimum and maximum for the Randomise Transform section instead. This will rotate the objects without affecting the size of the bounding box.
In both case you may get slight overlapping because the books are simply rotating in their original position. It's more complicated to set up, but for more accuracy you could use expressions to calculate the exact position of adjacent segments using the books width, height and angle and some trig. Attached below is an example of this technique if you wanted to take a look.