I don't know how the valve works so I cannot tell you. I don't think "scrunching" would be an issue, as they would be filled with water as would the pipe feeding them when the pump stops.

Why did you switch to time of day? What is the savings off-peak that makes it worthwhile? I have peak / off-peak here in NJ as well put the rates are something like 18 cents and 9 cents versus a flat rate of around 15 cents.

I did it because I have a 10KW PV array on my roof which generates about 12,000 kwh a year almost all during peak times. I always used to run my pump at night as I have a heatpump to heat the pool so it made sense. But after much thought I am now running the pump during the day as the heatpump is much more efficient when it is 80 degrees out then when it is 30-40 degrees at night. Also, I added a pair of 2' by 20' panels to supplement the heatpump so I need to run during the day for that too.