I haven't done 60, but even in the small number of sessions I've done, I've experienced a lot of the same recently. I've been on both sides of the hiring table in my 20-year career and these have been some of the worst hiring experiences I've seen.
I've not found anything new yet, but from what I've seen:
Companies that said no to me: They are looking for something very specific and a 20-year spikey profile doesn't fit with their narrow vision. These ones also had the worst technical tests as part of the 1h session - they were either very low level ("build a system to store strings") or super-high level ("Explain how you'd build a plugin system") and expecting perfect technical expertise.
Companies I've said no to: Red flags all over the place - one company put me through a 3.5h interview process (I should have said no, but I was curious - I said no before they made an offer) and did 3 very technical tests during that time.
In one interview they said they had no documentation, and one had already gone through a re-org and the hiring person already said others were leaving so this was a role to replace people.
And in all cases - clarity of role is missing from a lot of the descriptions. They have generic "Senior Developer" roles that require skill sets that in some orgs require a team of people. When you ask about the role there's no distinction of management vs leadership, one org said it would take months to fully onboard (so what would I be doing in the time up to then?).
It's amazing how consistent this is over the industry and I suspect it's in part when you let the development team run the hiring process instead of the HR department.