Most papers will tolerate careful soaking, but some will simply disintegrate. The problem is that it's very difficult to tell which papers can suffer soaking safely. If the paper is old, surface soil could cause "tide lines", which may not show up until the paper dries.
And then there's the question of whether and how much the inks will run. The risk of immediate & catastrophic failure is quite high.
And there's more...
A paper sheet's fibers have inconsistent density, and here's why that is a problem: The buffer that slows deterioration is carried into the fibers by an aqueous solution, which will soak more of the buffer into some parts of the paper than into other parts of the same sheet.
Even when the buffer is part of the manufactuiring process, it has limited life in lignin-bearing paper. Like antacids in our stomachs, the buffers become exhausted, and then the discoloration takes place -- later.
When the paper is impregnated with a buffering solution after-the-fact, the eventual discoloration is likely to be spotty. That is, where more of the buffer has soaked into the fibers, discoloration will happen less and/or later, than in areas where less buffer is taken into the fibers.
Personally, I consider deacidification to be a conservator's work.
Brande