I think it's sequential, but not sure.
It's certainly producing the second bud after the first was almost ready to open, unlike most of my hybrids which produce the whole spike of buds then start opening them. Whether it will hold a couple of flowers at once I'm not sure.
Yeah, I've left Phals that long before. My bulbo would start rotting new growths in that time, but the Phals generally cope. I also found a Phrag this morning which had been standing in water since Friday. I'm growing that in a variation of S/H and had forgotten to release the water
The good news is the Paph Pinocchio I left in water 2 weeks is still doing fine months later