I believe for NIW, hiring a experienced laywer to present your
case is necessary and sometime crititcal for your success.
Because it's may be tricky to convince the office that this case
satisfy the requirements of NIW
For EB1, maybe it's defferent, since there are clear requirements
of your evidence of accomplishments. If you are very storng in your research, DIY is no problem.
If this postdoc file his NIW by DIY without too much experience,
he/she may loose it.