It's good idea to increase length on some workouts?

In last autumn I started a customized plan for Christmas. Some workouts has 15-25 minutes or so at 65% at the end. Like Baird +6.
And after some years following several plans, I felt was good for my fitness.
And now I have started Medium SSBase 2. And I don’t see this kind of workouts with 15-25 minutes 65% at the end.
Should I add it to my 1 hour workouts?

2 posts were merged into an existing topic: Best way to add some volume?