The way I see it is similar, but maybe not as involved. I also suspect the Seed is always a Seed ... otherwise Rand essentially gave Elayne a one-off angreal creation. I got the impression that the Seed was something that could be used many times to create many angreal.

I assumed the Seed would be along the lines of a Well in terms of it only needing a moment of connection to do it's thing. I imagine that Elayne on her own would only be able to create an angreal that at maximum offered up her own strength. So Elayne (using your numbers) could create an angreal that gave 89 saidar, but she would be unable to channel at all for xx months. She could choose to make a 29 saidar angreal and still be able to channel at 60 for xx months, or she and Nynaeve could link and create a 186 strength angreal and each of them would be unable to channel or they could link with Egwene, Aviendha and Sharina and create a 186 angreal and have the weakening spread across the 5 individuals.

Perhaps sa'angreal were created when powerful circles linked and created them, or perhaps a sa'angreal required both men and women in the creation with the sex of the sa'angreal being determined by who led the circle? From the little we know about sa'angreal it seems that there was some kind of manufacturing process involved so it's possible these were created using the "standing flows" and some kind of machinery and thus had massive power available but in limited supply?