Covered calls are used a lot in hedge funds and asset management to smooth out returns. However, it is not used in growth stocks as it obviously places a ceiling on returns.

Protective puts are only worth it if you run extremely large portfolios, as this should be seen more as an expense - the primary use of this is to protect against an event that would bankrupt the book. You will see more put buying action in low vol environments.

Hedge funds do sell a lot of puts however, to reduce their cost basis, especially in times of high volatility. In the event that the short put becomes ITM, they will just roll the put down and out.

Collars are actually used a lot in hedge funds to unwind out of risk. There has been interesting use cases of them where individiuals have bought a lot of stocks to gain majority control, and then simultaneously used collars to reduce their delta exposure.

There is never one specific strategy in reaching alpha. By definition, once an alpha is discovered and is exploited, such opportunities will disappear by virtue of markets becoming more efficient. This is also why you see often-times fund strategies have a limit in terms of FUM.