Subject: Re: Wild-and-crazy idea
Using a weekly chart compare the close of QQQ to its 52-wk moving average. If the close is above the MA use TQQQ; if it closes below then exit.

I did look into that. Along with a bunch of other schemes & lookback intervals.
Here's the problem:
1/1/2000 to 8/11/2023 (CAGR's):
Untimed TQQQ: -5.4%
52 wk SMA TQQQ: 12.6%

But....
1/1/2000 - 1/1/2010:
Untimed TQQQ: -43.5%
52 wk SMA TQQQ: -4.9%

1/1/2010 - 8/11/2023:
Untimed TQQQ: 38.3%%
52 wk SMA TQQQ: 27.5%

Note: TQQQ inception date was 2/9/2010

The first 10 years was horrible, you had to use timing to not quite keep your head above water.
The next 13 years was great, although timing cut the CAGR drastically.

I do not think that anybody would stick to TQQQ in a period like the 2000-2010 years.