Understanding `yield*` in Effect.gen Functions

When writing an Effect.gen function, am I right in saying that we only need to

yield*

yield*

computations that specifically have type

Effect

Effect

in order for their effects to be executed?

For example, if we were to do a normal javascript file write statement inside an

Effect.gen

Effect.gen

, can we be assured their (untyped) side-effects will always happen?

Effect.gen(function*(){
  ...
  writeFile(...) 
  ...
}

Effect.gen(function*(){
  ...
  writeFile(...) 
  ...
}