Sometimes it takes me a long time to cum, other times it'll be less than 10 minutes. If you masturbate with vibes a lot, it might take longer for a human to get you off.

Also, to speed up an orgasm while masturbating, you can switch methods - start with fingers, switch to toy, finish in the shower using the shower head or faucet. Mmmm, think I'll head over to the erotic stories now