I hate to bring this up as I’m just starting to play and just getting into it, but I think it is wise to plan a head for a store bought item to speed up or cut time off of training or other such time based production/etc.
I know this tends to be a tricky subject and a slippery slope but if you set it up or plan for it, it can be something that keeps the game afloat and casual gamers that enjoy supporting games can dump their funds into to speed up their game progression.
Standard set ups you see in your standard games - click a gem, gold coin, ect and it subtracts “X” time off of something. You could do all sorts of stuff to limit or reward players that do this, or even make it part of some mission(s) reward. You could have a counter to keep track of players that use them verses those that don’t - as some people have goals of seeing how far they can get without using these options - while other work to be the best in the game in the shortest period. Plus this would allow you to put limits on how much you can speed up training. You can only use “y” speed ups per training, refining run, etc., etc.
I don’t mind the wait so far but know if I had the option I would probably use the speed-ups and money for game developers are always welcome I would think.