Which method is better for liquid crystal overdriving?
ad 1: it is completely wrong, you do always get the +5V if any of the switches is activated.  

My proposal: if the intervals can be determined as an even number of base time, for example: t1 equals to (t4-t3) and (t2-t1), (t3-t2), (t5-t4), (t6-t5) are N * t1, then you could use a synchrnous counter made of flip-flops and use those analog swithes to switch +Vd, -Vd.