I am just doing a saison with a good bit of lemon, mostly zest. My process is based upon the idea (do not know how well supported it is), that a lot of the wonderful oils you want are very volatile. For around 5 gallons I added zest and juice of 1 lemon initially with the yeast pitch to avoid anything going away due to heat. I prefer time over heat with hops as well being a huge fan of hopstands. Smelled brilliant combined with the rest, but after a week a lot of that hit was gone. Thus I added the zest of 2 more lemons to secondary for 4 days. Thinking about doing a final 1 lemon zest charge on bottling day.
Point is that these flavors are volatile and I recon you get the best extraction when you add them for some time when there is alcohol present, meaning secondary. That way you do not boil off any of the good stuff and the alcohol helps extract it. Not that different to dryhop really (still hopstand fan).