I would say commercial loads have not grown longer but that the frequency of the same commercial and more irritating per inquiry ads are now commonplace. Most syndicated programming has X number of avails and you cannot exceed that without your programming clock being off. You might speed up a show a tad or run closing credits and the start of the next show as a split screen to get another commercial or two slipped in.
Tall Guy is right. The place you have freedom is in local programming. That includes news blocks and movies. You can squeeze in all you want.