I learned the hard way on fuel one time.

Don't need that lesson again.
I have 36 usable, with an 8 gph top-end burn. 4 hours of flying would put me at 32 gallons used with 4 in reserve. Not nearly enough for my taste, especially since I've learned the hard way that fuel burn is far from an exact science. I do all my cruise flight planning on 3 hours legs or less, with an allowance to fly 3.5 if absolutely necessary (putting me at 28 used, 8 in reserve).
It helps that I have the old PA-12 glass sight gauges, in which you can't really see the bottom 4 gallons in either tank while in flight. Even though I still have an hour reserve at that point, looking out and seeing two bottomed out sight gauges provides strong incentive to start looking for a pump once I've flown much over 3 hours at cruise power.