Keep port and stbd fuel tanks connected or separate?

[The Dark Side]

My fuel tanks look to be connected via a valve. Previous owner has the valve open so the tanks are connected together. Is it common practice to do this or should I shut the connection valve so they can be independent of each other?

Cheers,

 

[firecadet613]

I keep mine closed so each engine pulls from its own tank. Otherwise, whichever tank with the least resistance may be feeding both.