> It might be slightly tedious with a paper schematic, but it's hardly impossible.
What may only be slightly tedious for you will often be error-prone for someone else.
>I don't see any value in drawing a line connecting the pin to all the other SDA/SCL lines.
The value is that the entire bus is visible at a glance. All conflicts are visible, and contention sources understandable. Though, you can also put this information in a note/table.
>That's completely independent of how you lay the schematic out or split it into functional blocks.
What I mean is that it's often also valuable to split a schematic out along functions rather than busses. If you have an I2C ADC with a bunch of analog stuff connected to it, that might fit its own sheet better. But if your weather station I2C bus has several simple devices like Flash, ALS, humidity sensor, RTC, barometer, and thermometer, placing them together on one sheet may make sense. I just mean tidyness varies with the contents of the room.
I am not really understanding the "at a glance" part. If there are no labels then you have to follow the wires. That seems more difficult, not easier.
You can split out all the components on the I2C bus onto a separate sheet (or not) regardless of whether you label or SDA and SCL lines or connect them with wires.
If the complexity of the attached subsystem is low enough, the wires can be used as a feature not a bug, like a map.
Imagine a home network diagram with a router, switches, and computers. You could draw each on their own sheet with names for each cable, but the purpose of each cable is clear from what it connects.
What may only be slightly tedious for you will often be error-prone for someone else.
>I don't see any value in drawing a line connecting the pin to all the other SDA/SCL lines.
The value is that the entire bus is visible at a glance. All conflicts are visible, and contention sources understandable. Though, you can also put this information in a note/table.
>That's completely independent of how you lay the schematic out or split it into functional blocks.
What I mean is that it's often also valuable to split a schematic out along functions rather than busses. If you have an I2C ADC with a bunch of analog stuff connected to it, that might fit its own sheet better. But if your weather station I2C bus has several simple devices like Flash, ALS, humidity sensor, RTC, barometer, and thermometer, placing them together on one sheet may make sense. I just mean tidyness varies with the contents of the room.