the question for me is: Did you find this to apply also to staying with valuation extremes like 1.3x (or lower), or only when you go far higher, much more into the middle of the valuation range?

Good question - I can't recall! Too much time has passed since I took a look at this. I hunted for the data/assumptions I used back then but failed to find it (another lesson learned for being more organized). So I was inspired to re-do the analysis using the 2x leverage example you mentioned and this time did a comprehensive analysis consisting of all permutations.

I've uploaded a heat map chart that summarizes the results showing CAGR for different thresholds:

https://ibb.co/P9QQ4NL

To read it, find the P/B value on the x-axis you would want to start applying 2x leverage at/below, and then trace it up to the y-axis value where you'd want to sell and go to cash at, re-buying (at long, 1x) once it dips below that value again. That's the CAGR the strategy would have yielded (not accounting for trading costs).

The pink entries at/below ~9% represent BRK's CAGR for buy and hold over this time period for comparison. Anything at/below these values are worse than B&H.

The results are quite a bit more favorable than I remembered from previously. I think this is because I assumed a smaller amount of leverage, 1.3x or 1.4x I think, since I was looking at using very DITM calls and was more risk averse. I think I also tried to take into account trading cost estimates, and I was looking at thresholds of leverage at P/B <=1.2 and going to cash at levels >=1.5 which maybe weren't the optimal cherry picked ones.

Keep in mind, while some of these numbers look very high, as you move further to the right on the x-axis, you're also spending a lot greater % of time invested at 2x leverage which adds additional risk.