Y-Phil mentions tweaking 'vols & buckets', and I fully agree. Also, that may take some experimenting to find the 'sweet spot' for each type of job...

This PC has a pair of now-ageing GeForce GTX 750 Ti cards driving four (4) displays. And, yes, a low-flying duty-cat who's just deleted a so-carefully crafted paragraph. For 'modest' scenes, Superfly, progressive, I've found 'vol-bounces & buckets' may both be set to 1024. If cards max-out and scene is blank or missing chunks, I back those off via 512, 256... down to 64, which is what CPU-only renders prefer, be they this PC's weary FX8350 (8 threads) or network-render 'Box' nimble Ryzen-7 1700x (16 threads)...

I have a bunch of 'presets', making it easy to configure render for type of job...

This set-up is no match for a modern GPU card with 'studio' driver complemented by Poser render support, but building 'Box' was a lot cheaper than upgrading to such...