I must admit that whenever I fly a PA28, particularly one with a 4-tank system, I ask myself why the heck this couldn't be automated in some way - since you never want to give the engine opportunity to "cough", you inevitably leave perfectly useable fuel in each tank.
There is at-least one good reason not to draw from multiple tanks - if you have an imbalance and empty one tank then the engine will stop despite fuel remaining in the other due to the system naturally trying to suck air from the empty tank. However, if you have tanks on the same level, and geometry such that you consistently feed from the lowest point of a combined (and linked) tank system then you can
Cessna 150/152/172 fuel systems have a balance hose (actually two, the lower feeding the fuel pump from it's mid point), so effectively only a single tank - this is particularly easy to do with a high wing system so there's a gravity-feed element to it which also effectively makes the length of hose between the tanks and the engine a form of crude "header tank". A few types genuinely do have header tanks - albeit mostly high-wing homebuilts.
So what's the solution for a low wing aeroplane like a Piper? In my opinion, link the tanks at their lowest points, and feed from the low point of that link hose (ideally via some kind of sump with a couple of litres capacity below both tanks) into the main engine fuel pump. It would be hard to retrofit onto a PA28, but very easy to design-in to a new low wing design.
G