Since August 8 I've been logging CBP's published wait for every US land crossing, every hour. The first clear finding from San Ysidro: weekdays and weekends are two different crossings. Weekdays are quietest around 10pm and worst around 11am. Weekends are quietest around 4am and worst around 4pm. Otay's weekend peak is 9pm, so on a Saturday afternoon Otay is often an hour faster.
Every crossing, hour by hour, is free here: skipthewait.app/border-wait-times
Tempo has logged CBP's published wait for every US land crossing, every hour, since Aug 8. Every crossing gets an hour-by-hour profile and a live number; set a threshold and it pings you when your crossing drops under it. Parks too. Free, no ads.