Aside from the production / storage buildings that were convertible to their advanced counterparts, my Forges served as the conversion medium for my Barracks, Hunter’s Lodge and Hero Academy. Not having VIP Pass purchased means I won’t have a second builder to switch back and forth on the fly. I kept one forge and plan to keep that as a forge because as much as this game wants or calls you to deviate from certain low level items, I still use it to craft battle items I still use (Healing Items, Arrows, Bombs, Dragon Attacks, Time Stops, Tornadoes), and when I am about to run into excess or close to maxing out my storage spaces, the forge will serve as a food / iron sink better than a Hunter’s Lodge because it had existed for shorter amount of time than the Forge, aside from the Giant Harpoons, everything else in there takes Titan Parts, and there aren’t as many of those lying around as the other ingredients.
One of the main reasons I was running TC20 x 3 24/7 and queued up was because I want to max my chance at getting every 5* season 1 hero. I kept my fourth one, which is a maxed building too as my general purpose training on the fly type building. Sure, I can use Heroes Academy to do faster trainings on the 1* and 2* feeders, but until SGG addresses it as a QOL fix, there is not Claim All button as there are in the TC. You had to collect one at a time from the HA. Besides, I have more uses for my HA than training fast feeders, when HA10 is usable for me, I can use the other function for Troop Re-training if needed. It helps to have options. Now that I got all the season 1 3* - 5*, I still plan on running TC20 x 3 so I can find 5* dupes to put in. I just haven’t seen one for a while and this might even drag on since I don’t spend nor do I summon with Gems often, even if it is just a tool, TC20 still remain my best odds of finding something to toss into the HA10 pot.