Eh.. It makes no difference.
Whatever it takes for you to feel like you're having fun.
I prefer to take it easy and enjoy my base as it slowly involves into something special.
I've seen worse playing the game "Maplestory" I've watched friends buy themselves right out of cars, apartments and even a few that dropped out of college to play the game and pump money into being the absolute best.
Honestly though aside from the builders huts you don't really need to spend gems on anything and though you won't be able to get the heroes maxed or the walls you can still pretty much achieve what the top 50 players achieve in a relatively "short" period of time. Most people I know who stayed at TH 7/8 easily make 6 million gold/exilir in a few hours and keep their workers permanently busy. I haven't did the math but it doesn't seem like it would take more than a couple months.
I'm just glad because of these few "whales" the game will remain free and updating because at the end of the day for me it's all about how much fun I'm having.