I have 3.94 GPA on 4.0 scale but I've really trouble in terms of time to prepare for both tests general and subject. I prefer to prepare for only math subject test. Could I apply to schools with only the math subject test, or is the general test a nearly-universal requirement?
Every university is different. The GRE is less used than in the past, but some universities still ask for it or even require it. COVID, along with a general realization of its limitations has resulted in some schools dropping it.
So, you need to explore the specific requirements of any university you plan on applying to. But you need to do that in any case. Good luck.