With the Setup seen in the screenshots i can harvest 4 Lines of sugarcane at the same time.
This needs the ability to break the sugarcane u stand in.
In the pre 1.13 versions its not possible to break the sugarcane u stand in anymore.
Environment
Linux Mint 18 Cinnamon 64-Bit
OpenJDK Runtime Environment (build 1.8.0_171-8u171-b11-0ubuntu0.16.04.1-b11)
OpenJDK 64-Bit Server VM (build 25.171-b11, mixed mode)
Can confirm in 1.13-pre3.