Ben Jackson wrote:

If you're flying long distances and want to cut the total time, the most
cost effective way is to carry enough fuel that you don't have to stop.
If you can cut a 30 minute fuel stop out of a C-172 flightplan it's like
adding 15kts.

Another way might be to get an instrument rating.

I only have one data point for this, but this spring a fleet of 4
Warriors took a club trip from TTA to IAD. It was a VFR day. The one
flying VFR put 6.1 hours on the hobbes. The three flying IFR all put
5.1 hours on. I was the VFR one. The ADIZ did not slow me down as far
as I can tell. As far as I can tell the penalty was due to:

1. Worse ATC service. Once in the ADIZ and class B, every time I was
switched to a different frequency, I had to wait for several stretches
for there to be a break in the servicing of IFR traffic before I could
even get acknowledged and get a vector. Not to mention how nervous you
can get flying right at the prohibited area (or later, right at the
airport at 3500) on the vector the last guy gave you and the new guy
hasn't acknowledged you for several minutes.

2. More vectoring. While my compatriots were being cleared direct to
Brooke VOR then to IAD, I was getting vectored around the RDU Class C,
and then once in the ADIZ and class B I was vectored all over the place
to basically get me out of the way while the IFR traffic landed, then
they worked me into a gap in the IFR traffic for landing. My first time
on a 13 mile final in a Warrior!

I don't know if this is typical, but assuming an instrutment rating
costs $5-6000 to get working the $/effective knot here might be a pretty
good number. So pilots who fly both IFR and VFR, is that experience
typical? Is better routing and radar service a good enough reason to
get the instrument rating, even if you don't plan to do much hard IFR?