[edited out]
Some thoughts:
If nobody can access your seed your won't need any passphrase,
if the seed was created with sufficient entropy ...which should always be questionable though!
Also, you are right, even a short passphrase will leave anyone who gets your seed in doubt if there even
is a hidden passphrase wallet and if it makes sense to put in the work to
look brute force for any.
A 128 bits phrase can secure your seed with the same security the seed secures your BTC,
if that's what you want/need for ease of mind.
Nice thing: totally independent from all that passphrase science is the PIN which can secure your Trezor 100% against seed extraction from the open source chip. If the PIN strong enough your device will be worthless to any attacker.
From this discussion, I think that I am starting to understand some of the ideas more also, and truely if you hafve to use a 37 or 39+ character pin, then holy fucking shit, you are not going to be using that wallet very often because Trezor frequently requires you to enter in the pin when you are doing various transactions and to confirm transactions.. and maybe it is just to wake up after a few minutes of inactivity and maybe some of those settings could be tweaked in order to not require the 37-39+ character pin every single time.. ..
I don't know the exact answer, even though I know what I do, and from time to time, I also tweak what I do order to try out new things.. and surely we can do what vapourminer suggested which then allows for various seed phrases to be entered each time we are going to use the trezor and maybe if we have a few days of trezor work we conduct a variety of transactions prior to deleting the seed from the device.. which does seem like a bit of extra work, too.. but maybe not a bad compromise..
I think that I had mentioned in another thread that I had some border crossing experiences in which I would not have the seed on my trezor but a different seed, so I am not totally opposed to the practice of carrying a trezor with either a dummy seed or no seed.. but then at some point, i had started to feel less comfortable with that particular seed, so I ended up switching seeds (creating a new wallet).
Another thing is that through the years, many of us might have old wallets and we may or may not be able to access them anymore, but there still could be questions about the extent of their value and even concerns that maybe some value could end up getting sent to them or maybe some historical fork could be extracted...so I am not even sure how to keep track of old wallets and old addresses, even though I have read some posts on the topic too.. with some members entering old wallet addresses into a bitcoin tracker (or watcher) and those seem a bit potentially dangerous practices too.. to be discovered to be watching certain bitcoin wallets/addresses might create inferences that you either own them or had owned them at one time... and then to have them in one place to be connected could be problematic too.. and some of us have probably already made some of those kinds of mistakes in terms of how we are managing our addresses.