Newbie question on edge joining

actually in reality it is fair enough to add less than that and perfect it on a TS, or whatever when you get it home. Of course this has implications on the design. Even if you got only half a blades thickness left, a TS will make quick work of it. Something I hadn't considerd as significant. OTOH, I had a dozen different strips cut from a 4' x 8; mdf for door jambs and had nothing to worry about.

"Do I need to get the edges perfect "

No, but if you ever can do "perfect" share your technique!

Though you never said, the assumption is that you chose biscuits because your design precludes using dowels through the one piece into the other as the doweling would show on the one surface.

Dowels have the advantage of a secure mechanical "bond" which the (recommended) wood glue enhances.

If there is nothing else holding the two boards together, I think the dowels would out perform the biscuits over time.

I may have a cheap BJ, but the slots it cuts and the standard (porter cable labeled) biscuits I bought do not mate tightly (I have pressed two biscuits in the one slot (that's tight!) to get the mechanical fit I prefer.

Your Biscuit Jointing technique may well result in a tighter fit.

By the way, if anyone knows (for certain) if I can get the blade of my BJ ground down to make thinner slots or a source for thinner 4" carbide blades for a BJ - I'm interested.

I, and lots of other people here, get perfect edges whenever we want. Do you have a specific question? I'll be glad to offer suggestions and possible solutions. I'm sure others would also chime in.

Why not cut the slots on a router table with a 3-wing slot cutter?

"Why not cut the slots on a router table with a 3-wing slot cutter?"

What, and waste all that $$pent on the Biscuit Joiner?

"I, and lots of other people here, get perfect edges whenever we want."

Wow, and do you walk on water as well?

Humor, apparently, doesn't translate well on these lists.

I was attempting a bit of tongue in cheek repartee - in my world, God does perfect, mere mortals come close at times.