The stories on this forum seem to indicate that everyone is different. Anyone who is continent by 6 months is probably going to do all right, but if not there will be residual issues (though also take into account that some consultants will categorise as "continent" a patient who leaks slightly and still needs a thin pad).
My experience sounds similar to your husband's, but I'm about 3 years further down the line. Continence slowly improved over the months following the operation, but I still leak a bit. I just get on with life using a pad - in my case most days now I only need the one. Just the same as you describe leakage gets worse in the evening. In follow-up appointments the doctor seemed to focus on "stress incontinence", that is when there is leakage to accompany a straining activity (like lifting a heavy item); however my experience is not usually stress incontinence as such but rather that straining seems to make the sphincter get tired earlier and then leak more that evening. Problems get worse days I do quite a lot of gardening, or get a bad cough, or as yesterday go for a country walk over rough ground for several hours.
It would be nice to be pad-free but actually I can get on with life just putting on a pad in the morning, and having a spare available for the odd occasion it is needed. (And although it is not what you are asking about, it was important for quality of life that one nerve instead of two turned out to be adequate for a perfectly good - if different - continuing sexual relationship).
My fingers are crossed for your husband, but the main thing is to make the most of what you have.