As expiry approaches the Greeks change character. vega shrinks toward nothing, theta per day rises sharply, and gamma concentrates at the money. A short-dated position is therefore a bet on price and path, barely at all on implied-volatility.
That profile rewards precision and punishes size. The same dollar of premium carries several times the intraday risk it would in a 45-day contract, and a position that was comfortable on Monday can be unmanageable on Thursday without the underlying having done anything unusual.
Example: the XYZ 45-day $50 call decays about $0.03 a day and has 0.06 gamma. The 2-day $50 call decays $0.28 a day and has 0.31 gamma. Same strike, same underlying, an entirely different instrument.
Related: zero-dte, gamma-risk, time-decay-curve, color-greek