The same level of acute risk is not more serious than if it were chronic, but it does justify more mitigation measures. It's like the difference between spending £1 every day for 40 years or £14,610 at once. If you can reduce the amount by 10% in each case you save the same amount, but it's a lot easier to save 10% on one big transactio, where you can put more effort into analysing the situation than to do it 14,610 times.
And, of course, an apparently one-off acute risk might turn out to recur, making mitigation measures better value. Similarly, the apparently chronic risk might decline, meaning effort put into mitigation might be uneconomical.