カレンダースプレッド - いつレッグインするか？

While single orders are safer, legging in allows you to be more selective about your entry points for each leg, potentially getting a better overall credit or debit. It's a trade-off between control and risk.

Never leg into an SPX calendar spread. The bid-ask on those options can move against you instantly. One order, one price, less stress.

I always put calendar spreads on as a single order. The slippage potential when legging into $SPX spreads can eat into your profits too much, especially with tighter markets. Just my two cents.

I find legging useful when I'm already in a position and want to adjust. For an initial entry, especially on a fast-moving underlying like SPX, a single order is usually the way to go to avoid unnecessary risk.