I think this concept of 0 DTE options growth causing a "Volmaggedon" is something that's getting too many turns in the press, but doesn't really have much merit that I can see, except for hype and clicks. @ETJ 's post with an article shows that 95% of the SPX 0 DTE trading growth has been institutional, not retail. And yes, CBOE is touting that 44% of total options volume is happening in the last week of Expiration. So, lots of activity providing thick and active markets. Great! Institutional traders will be either hedging or speculating. For hedging, the question of buying short dated puts, or some combos like Put Ratio Spreads can potentially be much cheaper and less of a drag on a portfolio than long-dated versions of the same. Apparently many are finding that to be true. Selling those Puts or Delta-negative combos to cash out during a market drop serves to blunt the down move. So no biggie there. Institutional speculators will be in Straddles, Strangles, all forms of Butterflies, and lots of other combinations. Except for the first two, they would be buying or selling combinations to exit or cover those positions. Net-net, they would be looking for Negative Delta, either through closing out or adjusting those positions. That I'll concede would create a pressure in the options market for the counter-parties (Market Makers in SPX) to pile onto the selling. But really - a drop of 1% to 5% in five minutes? I don't see hedge funds or other traders messing around in wide SPX options spreads working for a fill. I'd go straight to the /ES or other futures contracts and pay a tick to cross the market and get a quick fill. That's where the liquidity is to get a hedge or adjustment made quickly. With the /ES volumes alone, in a market selloff, there will be trillions of dollars moving to the downside. Additional capital at risk in 0 DTE options is still very small, and I doubt will move the needle much either way. To the OP's question about Pros/Cons, I think that trading 0 DTE options is like trading futures. It can cut both ways, and it's best to know what you are doing. You can make or lose a decent sum in a short time. Most strategies are trading for Premium decay during the day, and you have to watch the markets. Overall, the increased activity means those markets have gotten faster, busier, even more liquid (although the SPX is already *very* liquid), and Bid/Ask spreads are tighter. All good things in any market.
They are listed one week in advance so they are regular weekly options. They are nothing new, there have been m-w-f expiries around for a long time. You do not have to trade them on the last day only, you can buy and sell multiple days in advance just like with monthly and quarterly options.