I go in both directions using a credit card style diamond hone, 600 grit. You need to be sure you are not rolling over the cutting edge. If you do you will be dulling the tool instead of sharpening it.
If you use a grinder to sharpen then you have a hollow grind. The diamond file should make contact at 2 places, the tip and the heal of the bevel. The first time you hone a tool it will take a little longer to get the really good edge. After that is is very quick if you do it frequently. Takes me about 15 seconds for most tools or a bit longer if I waited too long.