[R-meta] When to skip an extra level?

[Timothy MacKenzie]

Dear Meta-analysis Community Members,

I want to get some clarity regarding when not to add an additional
level. I have found two posts and was wondering how they agree with
one another? (It seems the first one says is at odds with the second
one)

***This post: https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2018-July/000896.html
suggests that we should avoid adding an extra level (row id) in:

random = ~ 1 | study/outcome/id

if not so many "studies" have repeatedly used the same "outcome".

***This post: https://stat.ethz.ch/pipermail/r-sig-meta-analysis/2019-March/001479.html
(second message from the top) suggests that we should avoid adding an
extra level (study_id) in:

random = ~ 1 | paper_id/study_id/row_id

Arguing that "One can probably skip a level if the number of units at
a particular level is not much higher than the number of units at the
next level (the two variance components are then hard to distinguish).
So, for example, 200 "studies" in 180 "papers" is quite similar, so
one could probably *leave out the studies* level and only add random
effects for papers (the two variance components are then hard to
distinguish)."

Sincerely,
Tim