Courses complement self-directed learning
Since PIT was first developed there has been a synergy between providing formal courses (including supervision led by an expert) and self-directed learning.
This website provides many resources for practitioners to develop their skills by watching films, role plays, transcribing and analysing sessions, and structured peer supervision with recordings of sessions.
the latter can be described as a portfolio approach to education- it is generally formative rather than summative.
There is an ongoing debate in psychotherapy about how closely therapists should adhere to a model, as the evidence for improved outcomes is weak.
PIT-UK supports portfolio learning although there are also courses for those whose learning style prefers the external structure, and in some work settings it may be a requirement to prove competence.
There are many resources for self directed learning here