In the grand scheme of things? as long as its not plagiarism you can use whatever strategy works. As the old saying goes: a bad artist copies. A good artist steals.
Some speed painters take a photo and use that as a basis for their drawing. as it captures the mood, colours etc. in some cases its the only realistic choice when time is short. See the link below for an example:
View: https://www.youtube.com/watch?v=e2eTgIaWVRA
Theres plenty of tuts on how to draw the head andrew loomis one for example is pretty simple. i don't quite have the skill for lineart; i need the mess of scribbles and i need the underlaying structure etc. How some artists just draw a face infuriates me sometimes, probably because they practice like hell going to drawing classes and i do it for a hobby etc.
Must admit i do draw bald heads when i practice as well, but its mostly a cookie cutter process although theres no shame using references (in fact its encouraged). Sometimes i just copy other artists for practice to see if i can harness their powers or learn a thing or 2. When it comes to art i like to learn not just the how, but the why part.