I could go on on this subject forever, as I started out in sector mutual funds ages ago, and my second largest account still does nothing but make sector bets.
I have a model with a trading time horizon measured in years for this which breaks things down into five phases for either a bull or a bear:
Phase 1 - Extremely quiet price action, very low volatility (when measured over long intervals, not talking here about daily price movements, which can still be very violent).
Phase 2 - Momentum makes new 52 week highs (I have ways of measuring this), but no new 52 week highs in price. Volatility stays low.
Phase 3 - New 52 week highs in price coupled with new 52 week highs in momentum. Volatility measures start to rise.
Phase 4 - New 52 week highs in price but not in momentum. Volatility continues rising.
Phase 5 - Divergence: new highs in price, coupled with declining momentum. Volatility peaks. This is when it's time to sell. This is also phase 1 of a bear market. Bears then go through phases 2 through 4, except that for the word "highs" substitute "lows", and for rising volatility, substitute declining volatility, until you finally wind up back at phase 1, with little price movement and very low volatility.
According to what I'm seeing, the market in general and most sectors are in phases 3 or 4. A couple of sectors moved into phase 5 and I wound up selling, the most recent here being the utilities.
Note that the above is the ideal pattern, but frequently there are plenty of variations. Real life doesn't conform to a set pattern.
For instance, gold stocks, but not gold itself, is in the position of moving into that first phase from a bull market rather than a bear, having gone to phase 3 of a bull in its last upmove. But its consolidation after that has lasted so long that according to my model its right back in the first phase, as if it had just ended a bear and was preparing for takeoff. This only happens if something is in the midst of a true secular rather than cyclical bull market. (Gold itself is moving through phase 4 of a bear and into phase 5, which would put it back in phase 1 of a bull. This is normal, since gold stocks lead the gold price. But it's doing so without making new 52 week lows in price, which is, again, a sign that this sector is in the middle of a secular, instead of a cyclical, bull market.)
Interestingly, the S&P looked like it was in phase 4 and was getting into phase 5, although volatility did look too low for that to be true at the time. It's since abruptly stopped just before giving a sell signal, and now is looking like it might want to rewind itself to that same phase 1 that gold is now in. I'm watching this with a lot of interest. I don't think I've ever seen gold stocks and the S&P sync up their cycles, but there's a first time for everything.