The effective supervision is actually a very important factor. During my early plank days, there was always a wise old CFI who would help you to make the go/no go decision. When I moved on in later years to independent private strip flying from lonely uninhabited farmers fields, I realised how much I had depended without realising it on the wise advice at my elbow. Over a long period, numerous friends came very close to disaster in that situation, and in some cases too close.
It is very different making your own decisions without the support of a club/training school behind you, especially if you are low hours.