[Suggestion] Iron Storage / Production
Stronghold 1-20 allows you to work on 5x Iron storage and 4x mines at a time so you do not run into problems with total iron capacity and losing iron production.
Make one, or all, of the following changes to Iron Storage and Mines
Increase Stronghold’s innate storage ( 10 k iron, 10 k food, 30 recruits) each time the Stronghold levels. You could just use the same stat curve as iron storage and advanced iron storage.
Add iron production to Stronghold 21. You could use the same stat curve for Advanced Mine.
Instead of adding iron production to Stronghold, add iron BUNDLE production to stronghold. Use the base stat curve for mines, but reduce the amount by 80% and produce 10k iron BUNDLES ( see Beta Path of Valor ) this would help with the complex, unfriendly, punitive design of Advanced Iron Storage.
Watchtower produces Y% of iron as 10K iron BUNDLES.
Advanced mines produce X% of iron as 10k iron BUNDLES.
Add iron storage ( not production storage capacity. see Advanced House for difference ) to Watchtower. This would also encourage leveling Watchtower. You could just use the same stat curve as iron storage.
Mines still produce while being updated. You could limit the percentage of production. 5% per Stronghold level.
All Advanced iron storage unlocks at Stronghold 21. You could limit the Advanced iron storage maximum level at each Stronghold level.
You can unlock Legendary training ( RT20 ) and Super mana potion ( 100% mana ) without maximum buildings. The trend of Advanced Buildings to require a spreadsheet and maximum buildings to unlock everything for a mobile game is very disturbing.