Garmin Upgrade

I cannot say for certain, but I have seen an article posted here, that if you let the unit sit powered on under open sky for 20 minutes it will get a better lock on the satellites in your area. This will, in turn, allow for faster location of satellites in the future.

I'm sure others might have other thoughts on the validity of this.

This is true only if "future' is a very, very short period of time. The 24 satellites used for GPSing are constantly orbitting the earth. Once the GPS locks in on the satellites, you should be able to turn if off and back on and see it acquire the satellites very quickly. This is because it 'remembers' which satellite it found and where it found them. If you waited until the satellites moved enough that the GPS couldn't find the ones it remembered, it will have to re-acquire new satellites and hence take longer to acquire. The same is true if you turn off the GPS and move 500 miles or more.

Once you have acquired the satellites, leaving the unit turned on for a longer period of time should have no long term impact on future satellite acquision times.

That is not true for all Garmin models. Some support SiRF InstantfixII. http://www.sirf.com/products/location2_services.html