I looked only at 1990 and above as the numbers of albums in our collection before that made analysis pointless.
I had expected that the lengths of albums (by time and/or by number of tracks) would increase over time.
In fact I found the averages per year to be statistically steady at around 50 minutes to a little over an hour long, and the number of tracks between 12 and 16.
I had thought tracks and total time would go up purely due to the habit these days of including "bonus tracks" on newly released albums. This doesn't seem to be the case.
If anything, the trend in both total album time and number of tracks is slightly shorter and slightly less tracks.
It's possible that past year totals are diluted by the fact often the "backfill" albums bought are re-releases/remasters with bonus tracks. It would take a fair amount of filtering to check, and I don't care enough to go to that sort of effort.