i would also add a few things on develop (they actually concerns all TFB cards but worth the recall for develop)
It is also good when you have cards that are really good at first but whose value is either null or greatly decreased after a certain point in the game. Those type of cards means you will have trash folder with a decent cost in the middle game. in which cases a develop can work pretty good at recycling them into more useful cards at this point.
Example of those kinds of effects are:
early game attackers: Seahag, Cutpurse, Swindler
early game trashers: Moneylender, Loan, Outlook
early game big buyer: Baron, Horsetrader, Coppersmith
cards mostly powerful when gained/buyed: main contender is IGG
You would still need good cards 1 less and 1 more than those cards (especially with the ones costing 3, you don't want to gain an unwanted estate) but knowing that you will have cards that will be dead or nearly so midgame can encourage you to grab 1 develop for the ramping up phase of an engine.