Hi Peter
Some good thoughts. I think it can also depend on the size of your dojo/organisation and who you get to practice with regularly.
There's a heap of value in just practising (with care and attention) - and doing it with others, outside your normal practice circuit, can of itself be very valuable.
Dealing with different types of people is in itself educational - although you need to be careful to look after yourself appropriately sometimes - so don't let yourself be injured because of someone else's "issues". Not always easy, particularly if you are significantly lower graded than your partner.
In my experience, if you can even pick up a single key thought/insight at a seminar, then it is probably worth it. More than one then you are in clover! Develop it and work it - stuff starts to happen.
I saw a video by Dave Ruebens (Yoshinkan, now 6th dan), which I really like (I have trained with him a few times in the past):
https://www.youtube.com/watch?v=XBUG7F4VCH4
"There are people here who have done X technique hundreds or thousands or tens of thousands of times - what difference will it make to do it a few more times...?" I don't train Yoshinkan, so the details he explains are not necessarily appropriate for me - but the intent/approach, absolutely.
Robert