How does less basal raise blood sugars fast enough?

I'm always curious about this. People say less basal from the pump helps them with lows, but if insulin takes anywhere from 15-30 mins to start working, how does reducing basal actually help mitigate a low? Doesn't that mean the basal slowing down and then eventually stopping still lags 15-30m behind my actual numbers? I know it would help logistically, but insulin is kinda slow, so how do we end up seeing the affects of reduced basal vs just treating the low ourselves? Sorry if this is dumb lol.