Purpose of analog watch dial where first 20 seconds of dial is in contrasting color?

[StillShaving]

Have noticed a few watches where the first third of the dial is highlighted, enough to make me suspect there is a functional reason and not just fashion. Hopefully someone can educate me on its purpose? Is there a reason to highlight the first 20 seconds of a minute (the second numbers also being accented)? I thought I saw this on other brands, but when I search now I just see a few Seikos. Hopefully it is not some big 4:20 joke inside joke? A pictures below.

Seiko SNKK27:



Seiko SNK375K:

[generic0]

I think diving...diving...uh, not being a diver myself, I think there's something about 20 minutes of dive time being important.
IWC aquatimers also have this scheme I believe.

Anyway, my guess.

[drocu]

"Bezel markings
Most contemporary dive watches with conspicuous 15 or 20 minute markings on their bezels are the result of copying a Rolex bezel design of the 1950s. Back then divers typically planned a dive to a certain maximum depth based on now obsolete US Navy dive tables, and dove according to the planned dive profile. If the dive profile allowed a bottom time of 35 minutes the diver, upon entering the water, would set the marker on the bezel, 35 minutes ahead of the minute hand. The diver calculated this with the 60 - bottom time formulae (60 - 35 = 25, for 35 minutes bottom time the diver would align the 25 minute bezel-mark with the minute hand). Once the minute hand reached the main-marker on the bezel the diver would begin his ascent to the surface. The 15 or 20 minute scale helped with timing the ascent and whatever safety stop the diver deemed necessary. For contemporary diving methods the 15 or 20 minute "count-down" bezel is quite antiquated.<sup>[19]"

http://en.wikipedia.org/wiki/Diving_watch</sup>

[ouch]

It's for timing shaves.

[mdunn]

With a rotating bezel it makes sense... With these ones i suspect it's just for looks

[blantyre]

In the watch that's pictured it's purely for styling, like the offset button I think.

[AABCDS]

It's for timing shaves.

I got a laugh out of this one.

[maxman]

I use it for timing muffins in the oven.
mmmmmm.

[Bobtrumpet]

It's for timing shaves.

I got a laugh out of this one.

Oh, man, don't encourage him!

[Blondie]

In the watch that's pictured it's purely for styling, like the offset button I think.

The offset crown is for comfort. It doesn't dig in to your wrist when it is at the 4 o'clock position like that.