Depends what you are doing. Digital circuits are not really that hard. You are just repeating known patterns and keeping the voltage in correct level (3V3, 5V,

Depends what you are doing. Digital circuits are not really that hard. You are just repeating known patterns and keeping the voltage in correct level (3V3, 5V, ...) unless you are doing some bleeding edge stuff in GHz range. And because these circuits are very deterministic it is also simple to emulate them down to the transistor Analogue circuits on the other hand are massive PITA. They have their own mind, reacting to the smallest of fields and very hard to work with.