Not sure of the exact proportion, or where from, but yes several Met
services every hour terminate at Baker Street - it may be close to a
third.

Incidentally, those that continue to the city, certainly in the peak,
do not always get as far as Aldgate some terminate at Moorgate as
well.

The Met is also unusual in that, unlike other lines, there is a
concept of fast and slow trains the longer distant Met services being
non-stop over certain sections.

That's maybe where the different types of stock come in useful.

My observations at Aldgate, last I was there, showed the full set of
Met destinations being served so presumably it's a proportion of each
service that terminates at Baker Street.

I always find Baker St to be a bit of a pain, changing and traveling
onwards eastbound, trying to second guess which platform is going to
have the next service.

I just follow the crowd which seems to work.