Anecdote, my situation, 1PW is plenty.
I'm in Los Angeles, SCE as well.
I had 4.8KWh solar installed in 2018, I added 1PW and 1.8KWh of extra solar (West facing) last year.
I'm on the 4pm-9pm TOU plan which in the summer is 3x the off-peak cost.
Solar production is about 40KWh per day now.
Daily home usage is about 30KWh, so 1PW is not quite enough to make me fully self sufficient.
But with the advanced time-of-use scheduling, on a clear day the PW is fully charged by around noon, I'm feeding excess into the grid until 4pm, then both feeding back to the grid from 4pm to around 7pm, and running the house from the PW until 10pm or later
So I'm getting full benefit of the TOU rate arbitrage, and I have the peace of mind of the backup for the odd grid disconnections.
And any time that SCE raises the peak rates, it benefits me.
I expect this to be much better month-to-month that previously with no PowerWall.
Winter months are going to be a bit lean, but that needs more solar, not more PW.
Yes, I fully believe the value you get by being mostly agnostic to TOU shenanigans has an implied ROI even if the actually financial benefit is hard to quantify.
What you describe is what I originally wanted to achieve back in 2020; and I was surprised (errr "shocked" pun) to learn nobody I spoke with (even Tesla) was willing to install a partial home backup solution that would also have TOU benefit the way you described.
It wasn't until I got on TMC and @Vines was here to help assure that such a design was possible. Every PV+ESS quote I had received simply had a single battery providing a mini-backup for a small load center and absolutely no upstream energy sharing when the utility was online.