What comparison can be made regarding the timescales of the fusion cycles in a high-mass star after core hydrogen depletion?

Each subsequent fusion cycle is shorter-lived than the one preceding it.

While the initial core hydrogen burning phase on the Main Sequence can persist for millions of years in a massive star, the evolutionary speed increases dramatically once that fuel is exhausted. The subsequent stages, such as helium burning, carbon burning, and further reactions, accelerate quickly. This is because the star must achieve exponentially higher core temperatures to ignite the next element in the sequence, leading to increasingly shorter lifespans for each successive fuel source. For instance, the final silicon burning stage might last only a single day, illustrating this accelerating instability.