Add cheese machine flow, save enough 10 sets, harvest and load the car every day, with 3000 experiences and 20000 gold coins at a time. Money will not be a problem soon, and the upgrade will be quite fast. However, this requires you to have the trumpet of the ox party as a support. Basically, 1 cow provides 1 milking machine, 10 cow can solve it. In addition, a small soybean is needed to feed the cattle.

That's what I did. I collected 10 milk machines, harvested and loaded them, and upgraded them quickly. Besides, I usually have 60w ~ 100 W in cash, so it's not a problem to buy anything. Now I am a size 40 large, 33, 34, 36 and 28 small, which is the trouble of switching between different sizes every day.

I hope my answer is helpful to you. Have fun.