Having been made a co-trustee on my parent's trust, along with getting power of attorney, was extremely helpful after their deaths. After my mom died, my dad was already 87, and simply not familiar with everything that needed to be done, especially on the computer and online side, where you have to spend a lot of time these days. Even me guiding him through it would have been a lot more work than me just doing it as a surviving co-trustee. Letting me handle everything let him rest and recover.
After my dad died is when I really saw how important this was. Things like the bank accounts were a breeze. In and out of the bank in less than an hour making simple paperwork changes regarding names on the accounts. Had there not been a trust, I'd still be dealing with account holds, transfer of funds, closing accounts, etc. Real property was also (mostly) a breeze, with simple transfers of title. File a couple of forms, and a month later new title was in and I was able to handle selling assets and distributing inheritance for his will.
I put in the "mostly" above because stinking California has new rules that make people jump through a few more hoops, and I'll have some CA tax crap to handle with my CPA for this tax year. Otherwise it would have all been even easier for a trust filed somewhere in America. My personal trust is still filed in CA, but I have an appointment with my attorney here in JAN to refile the trust in Idaho.