Use 'twofold' to stress the quantitative increase or the doubled nature of something. The project's complexity is twofold since last year.
Pro Tip 2/3
Explicit Contrast
'Twofold' often sets up a contrast or comparison between two distinct elements or factors. The benefit is twofold: cost efficiency and increased productivity.
Pro Tip 3/3
No Multiplication
'Twofold' refers to doubling, not multiplying by any other number. Our sales saw a twofold increase, not threefold.