Been using Guitar Honey for years...I have a bunch of guitars with unfinished rosewood necks so twice a year I slap it on and wipe it off...
https://www.amazon.com/Gerlitz-GEGHO-Gui ... B000EEJF4O
If you dont do this on the softer type woods your fretboards will start to dry and crack, fret ends will begin to pop, your frets will loosen up etc...you just take any type of rosewood oil and put it on for a minute or 2 and then clean it off...its just allowing the board to absorb moisture so it doesnt contract as it dries out and jack up your frets, change the level, etc...and also loosens up any crud that has accumulated so it can be wiped off.
With maple, you shouldnt use oil....99% of the time maple boards are already sealed, so it would be like oiling the body of your guitar...its just not needed. Plus maple is MUCH harder, less pourus...hences doesnt retain or lose moisture in the same fashion as rosewoods and ebony's...I dont beleive it has the same moisture content either...hence why builders can "bale" a maple neck and remove even MORE moisture and make it a more stable neck.
With maple you should just be cleaning the neck, not adding moisture to it. Guys clean them with lighter fluid or naptha...just coat it, allow it to loosen up the junk, and clean it off...use steel wool etc...
As far as the "experts" opinion about it rotting the frets...you shouldnt be "soaking" the board down, just adding a light coat to your fretboard, allowing the wood to absorb what its lost and and cleaning off all the excess. You dont submerge the board with the stuff. If everything is "proper" on your board yo will never have issues....loose frets and what not may have issues, as the cleaning and the oil will continue to loosen them up...but I have absolutely NEVER heard someone say rosewood oil rotted their boards...LOL...its produced FROM WOOD...so how can it possibly rot wood...its more that all the dirt, sweat, salt etc...from your hands got into the small spaces and rotted it vice the oil used to clean it.
If you live someplace mild, where your relative humidity is 40-50% all year then you should clean/treat your rosewood boards twice a year...if you live in the desert or someplace really cold where your heater is coming on all winter and the humidity is like 5% for months at a time them you probably should do it more often....its easy enough to see your fretboard changing color and getting a lighter shade...slap some oil on it and it will return to its original dark shade and you can literally see it absorbing the oil in the center of your frets when you do it....
Here is another decent article...
http://www.daddario.com/upload/FretboardCare2_1879.pdf