What seems like forever ago there were no 'fuel blocks' but individual items that were placed in a POS and consumed based on tower usage. Now its just blocks, 40 for large standard tower per hour in a wormhole (no sovereignty). Building the blocks inside the wormhole is cheaper if you have the right planets but it introduces complexity. Min / Maxing this in my opinion brings me to building fuel in hisec using items purchased from buy orders set up in smaller trade hubs. Exporting some of the lower items from the wormhole such as coolant, oxygen, mechanical parts to hisec turned into fuel blocks and returned to the wormhole.
Buy orders fill up with some babysitting, but I have to update other orders anyways. Stockpile a little of this, a little of that, produce the fuel then haul it in when there is a good static. Less to worry about, less to store inside the wormhole if it does go sour and most importantly more of my sanity kept.