Is it strict for the following adjectives or verbs should be followed by "should" or is it flexible to be replaced by an infinitive? Which do you use more? Do you use should form more or infinitive form more?

*subjective judgement or emotion- necessary, essential, important, desirable
ex)It is surprising that he should say so.(he says so)
ex)I regret he should worry about it.(he worries about it)
ex)It is a pity that he should miss such a golden opportunity.(he misses such a golden opportunity)