I think, both ways are having almost same advantage and disadvantage.

Some projects we starts, while we already know so many basics about. for this kind of projects, proper method can be easily implemented, in order to save time during trial and error.

The same way some projects we start without having much of background knowledge, and we depends on cpu behaviour versus our requirements. for this kind of project we have no choice but to run on trial & error basis.

Moreover, we all do not have high quality emulator etc. nor we can afford to buy one, as hobbyest or begineer, so we have to rely on some freeware software simulator etc. Those might not offer a required degree of debugging what our loosely developed code needs, at this point we have to get the enough background knowledge of our project and write a reasonably "tight" code with some breakpoints.

I personally use both of the above method, but I like to be more precise while writing the code.

Rauf