Land is not useless, if you have to little of it happiness drops. Tech causes your NS to grow faster than anything else, nit slower. Try and stick to the following ratios: infra:tech 10:1 infra:land 2:1 Your nation should grow nicely if you stick to these. I use these ratios and use the infra growth strategy and my nation does quite well. There are faster methods but I like to stick to a strategy that isn't to dependent on outside factors like trade.