Serious investors don’t typically trade in “naked” shorts. They usually cover the downside risk with an “at-the-money” call option (the right to buy shares at the current trading price). If the price goes down by an amount that exceeds the premium of the option, then they make money. If the price goes up, then they only lose the option premium, because they can use the call to re-buy the shares to return.

You can either run this strategy repeatedly, using 3-month options, or buy extremely long-term options and keep it open for as long as the options last.

... also, a short sale doesn’t have a time limit. You can be short as long as you want. However, if prices go up, then the debt in your margin account also goes up, and you might get a “margin call” - either deposit more capital, or close out some leveraged positions.

Margin calls are the nightmare scenarios for short sellers, since they can force you to buy out at the worst possible time.

As long as you meet the collateral requirements of whoever is lending you the shares, you can be short for as long as you like really.

You just buy a new short position. Also you can have a short position lasting a minute, an hour, a day, a week, a month.

(typically a broker will insist you have sufficient collateral period to indicate you can fulfil the short position).

Like a gambler, the next hand is always going to win.