I was talking to a winery owner about this subject a couple weeks ago. He brought up a good point about residual sugar. If your wine is dry there is far less of a chance for bacteria to grow so you have a lot more leeway with sulfites. Like myself, he felt you’re risking over exposure to oxygen and other contaminants more than any benefit you’re gaining from excessive racking. Now if it’s a sweet or semi-sweet wine, sulfite levels become much more important as they’re more likely to contaminate and spoil. I don’t make sweet wines usually so I can’t really comment on this, but I thought the whole conversation was interesting to hear from a professional’s perspective.
I myself rack once around 1.010-1.020. Again in a few weeks after the majority of the gross lees drops. Then one more time in a couple months after the majority of the rest of the lees drops, then that’s it. I add sulfates each racking but not before bottling. I hate that sulfite smell/taste you get with some commercial wines, so I avoid it right before bottling. I’ve yet to have a problem, even with wines up to 3 years in the bottle *knock on wood*. I’ve never had any make it past 3 years lol.