100% agreed about there not being an on/off switch for pricing, real estate pricing sticks high, and it takes a shock to make people reevaluate what they thought there property was worth. The very very minor increases in supply when there is massive pent up demand will not alleviate prices much, even if it staves off price increases.
Anecdotal obviously, but the closest one to me has been consistently over 50% empty due to bad construction and design, with no interest in fixing it to fill in the leaking units. Another 90 unit one has had trouble renting at the "luxury apartment" rates they were built to get because they looked landlord special day 1. They haven't lowered rents, only left units vacant.
Anecdotally (as well), no small-time landlord I know wants vacancies over accepting lower rents. Almost all of them, however, would prefer a vacancy over getting a problem tenant who will be late in rent, not pay at all, or trash the place. This effect is especially strong in places with strong tenant protection laws.
Professional management companies of big apartments might be different.
Note that the above limitations also limit how much can be invested this way. Most property won't go up by enough to be worth the investment costs.
Over what window?
There's clearly already a pent up demand for housing due to it currently being unaffordable. There's also clearly already a demand for speculative investment real estate, some of which is also pent up due to rising prices and constrained supply.
If the investors are still going to be in the market at the current price, and they snap up all available supply, then the price for housing is not going to come down immediately. It will only come down if you increase the supply to more than the demand of the investors. Only then will the price come down, and then people who just need a place to live may engage with the market.
The prices coming down isn't a simple on/off switch, especially in a market as complex as real estate.