That kind of thing worked well when Weinstein used it--kind of like the 200-day MA when Trader Vic first talked about it. Starting in the early 90s, enough people started using software (dial-up with EOD back then) that markets got much choppier and whipsawing ruined most simple trend-following. I ran a back test with a 7-month (similar to 30 week) MA traded on an end-of-week basis and it underfperformed the S&P 500 pretty badly since 1994. 7.32% for SPY vs. 10.37% for buy/hold and a 38% max drawdown vs. 50% for buy-and-hold. It underperformed according to Sharpe and Sortino ratios.Or you could just buy S&P 500 ETF (Not much difference from S&P100) and move in and out of the market on a trend line break.
Weinstein used a 30 week ma. Long when above and in cash when below. You get the odd whipsaw but it keeps you out of the big drops.
I use something similar with individual stocks and it kept me out of the 2008 and 2020 drops.
Having said that, I'd think a trend-following system with daily entries/exits would probably get whipsawed much worse. With a lot of work, you might design one that does well in backtests but I think it would fall apart in real time.
If I do this, I will make it an ET Journal and ya'all can raz me about my craziness. When I golf I love to "trash talk" so I can take it as well.