More on flaps

I have wondered why we bother with 'flaps zero = in trail'; I have not been able to discern any significant difference in the way plane handles or speed whether flaps are in reflex = -3 deg or in trail = 0 deg. I understand the speed limit for the zero deg position because the flap is not retracted up against the rear spar. Why not use just three settings of -3 deg, 15 deg and 30 deg? Anyone have a good reason for using four positions, other than Vans suggests it?

add

I actually think Vans removed the flaps 0 speed limit...

I use just 3 positions (-3, 15, 30) and always takeoff with 15 to minimize distance and maintain the habit of retracting after takeoff. If you takeoff with flaps retracted it’s probably better to use 0 than -3.

I’ve tried -3 & 0 in cruise and noticed a 1-2 kt slower speed when in 0.

I usually takeoff with flaps in-trail. Slightly shorter ground run, but no worries about exceeding flap limits (see above post).