Why is it that upgrades take so long? This has been a topic in the game since day 1. We've had buildings, plats, etc with instant upgrades, some that take hours while most take days even as much as 10 days to complete. Even with coining, upgrades can be expensive as hell. Changing a turret platform for example should be instant or at the most a few hours. Trying to keep up with the seemingly constant inflow of new stuff combined with the lengthy upgrade time is crazy. The frustration this causes is in part the reason some players leave the game.... it creates an atmosphere where some feel it is impossible to even try to keep up.
As a suggestion, shorten upgrade times on everything, leave the "cost" (oil/metal/thor) as it is for each upgrade level. If the current upgrade time on a building is say, 3 days, make it 1 day. If it's 10 days, make it 3 days. When comparing the change or upgrade of a turret platform to a building for example, the platform should be hours instead of days if not instant. Add in thor to the "cost" of changing to the new platforms if necessary. Players bust tail to get the 80 parts for an omega unit then have to wait days to max it -for example Herald is 38d to get to level 20 and another 90d to max once Omega (from lvl 22 to lvl 30 is 10 days ea).
Most understand the business side of the game and making money is the key but the frustration caused by having to wait and wait is part of what pushes players away.