No, it isn't. And it never will be. It is just a lazy way of doing things.
Whatever time you think to save with this method, it all gets lost with the 1 week of drying out your keyboard.
Water quality is highly important for the fool that attempts to do this anyway. It isn't the water that is killing your electronics, it is the additives that eat away the connection lines on the board. That takes a few weeks and you'll end up with a busted keyboard. So, never ever expose electronics to any type of water if you can prevent it.
A spent (yet clean) toothbrush, a damp cloth and a tool to remove key caps is all you need to clean up a mechanical keyboard and should take about an hour, maybe two.
Membrane keyboards usually consist of two halves. The top half contains the top with all the keys. You should disassemble your keyboard and you can safely clean the top half with water, a sponge and soap to do the dishes manually. First, use a pretty strong stream of water to clean out the gunk, like hair, food and other bigger "bits", then apply the sponge with soap to get rid of the remainder. Most, if not all ink spots disappear as well. Then use the same stream of water to get rid of the soap. Let it leak out for a bit, then take the top half outside and wave the top half with force. Centrifugal forces will remove most of the water that remained.
After that you'll need a drying cloth to wipe the rest. The top half is now clean and ready for re-assembly. Total time: 30 minutes with a gunky keyboard. Been doing that myself for almost 15 years now and haven't lost a keyboard since. And I usually clean them every 6 months or so. Then it takes about 15 minutes as keyboards don't have that much time to build up gunk.
However, this method will remove lubricant at some point or another, which results in one or more keys being more or less stuck. If that happens, I use graphite in powder form in the places that I think cause friction and in no time the key(s) work(s) again like new.
Bought those keyboards for a marvelous price (about 10 USD each) almost 15 years ago and while they do show some wear and tear after that period of extensive use and (partial) exposition to sunlight, they still work as they should and the employees here still love to work with them. Why did it never occur to me.. You can wash a keyboard in water.
Seriously, these are very good keyboards. Whether you get these with P/S2 or USB connector, you won't be disappointed.