yea the spraying and drying is one thing. but I'm worried more about the time to unbuild and rebuild the bike. I assume the fork and crank spindle have to be removed to do it correctly?
Yes, at the least the fork, seatpost, and bottom bracket should be removed so you can reach the interior of all of the main tubes and stays. You can leave the headset cups in place and any overspray or runs will clean up with mineral spirits, kerosene or WD-40.
Disassembly, if you have the needed tools and knowledge, shouldn't take more than 15- 20 minutes. Reassembly will not be a whole lot longer. If, for convenience, you disconnect all of the brake and shift cables to allow the bars and styem to be placed aside, add a bit of reassembly time to get the brakes and shifting reset. Since this is a one-time job, doing it right is worth the effort.