Hi Nellie,
I agree with the importance of developing critical reflection. Learners need to have the skills to evaluate what they learn and to write about it; that takes time and practice. I think these are improved by taking the time to write.
Evaluations of self learning can incorporate the reflective process to one's own learning. It would be good if we all took time to ask ourselves the essence of what we are learning. This might help learners (all of us) develop a sense of how to help ourselves and others. The evaluation's benefit -- to what purpose -- perhaps, mainly to improve recognition of what is actually learned and be credited by self and sometimes others.