1. The drains are NOT 1 1/4" pipe
2. The size of the snake's head is what is important
3. A 3/4" snake will NOT fit in to your drain lines through the sink openings
4. The vertical stacks seldom need snaking
5. If the piping was installed correctly, and you are not in Philadelphia, there are portions of the drain lines that are unique to each floor and a snake down the main line would not clear them.
6. I consider "preventive snaking" to be a waste of time and possibly a contributor to stoppages, because you cannot usually run sufficient water to flush out whatever you dislodge.
7. With preventive snaking you never know if you actually went far enough to reach the potential clog area.
8. It may be "inconvenient", but I only recommend snaking when a drain stops up. That way you know when you have gone far enough and it is clear, the backed up water creates a flood to flush the pipe.