I bought Tonga Treat Mango Charm pack for a table runner 'Little Charm' project at my open class (I have to buy fabric from the store to take the class). I am so happy the pattern did not call for 5" squares, because their 5" is off. Anything bigger than 4 1/2 would have not squared up so good thing 4 1/4 is all that was need for most of it and I had leftovers to deal with the rest. It called for 19 charms but I used more.
I am still in FQ-recovery from buying FQ's for a hand-dye project. One FQ was 16 1/2 x 23! Now I know the game, I can play by their rules. Or should I say 'rulers'?
I have never tried turnovers or whatever little foodie thing they call the bigger blocks, but I would recommend buying that way only if it is a quickie not subject to actual measurements as opposed to relative measurements, and if you can't play with your stash and accomplish the same thing.