Maybe I'm blind, but I cannot see any good reason for that kind of changes. It feels like changing sth just because it has been unchanged too long.
But, if you really think it necessary to slow upgrades down, why not just force units to go "fortified" or "sleep" next turn (or x turns)?
But, if you really think it necessary to slow upgrades down, why not just force units to go "fortified" or "sleep" next turn (or x turns)?