W2 does need a soak, 20 minutes isn't all that long. The vanadium in W2 will pin grain boundaries, so as long as the temp is kept tight, and under 1500F, best 1460-1475, then you could probably soak W2 for hours without any discernible grain growth, or doing anything detrimental. The reason W2 needs the soak is because it is hyper-eutectoid (extra carbon). There are 2 ways to get that extra carbon in solution.....temp and time. To put that extra carbon in solution with temp (1500f+), then you get some unwanted problems.....RC numbers actually go DOWN, retained austenite goes UP, and larger percentage of plate marteniste instead of favorable lathe martensite. The other way to put that extra carbon in solution is time. Use 1475F, with a soak. Often 10 minutes is recommended, but thicker pieces may need longer soaks, and it should not be blowing up the aus grain.
I recently did some testing on 1.2442, which is O7, or O1 on steroids. Did a 20 minute soak at 1490F, broke the blade to check grain size, and it looked exactly like the grain of a file or drill bit. That is to say...just a gray surface with no "grain" or "texture". This alloy does not have any vanadium, but plenty o tungsten, which does the same job as vanadium.
Decarb is by FAR the biggest cluprit in "why didn't my blade harden?" threads. It can often be much deeper than anticipated. I highly recommend ATP-641, as it will stop decarb and scale dead in it's tracks. I am finding out that some alloys only need a thin wash, others like 1.2442 need a thicker layer.