Thank you so much for playing and for the detailed feedback!
What you felt is pretty normal for the start of the game. In the first shifts the lamp is short and coins come in slowly, but as you upgrade your lamp, your pickaxe and your digging, you'll have plenty of time to dig wherever you want. The nights work the other way around: they start gentle so you can learn, but the deeper you dig and the greedier you get, the tougher they become. Later on they get a lot more challenging, especially with the bosses and the monsters from the deeper layers.
Thanks again for the kind words, and for taking the time to write this!