Should I switch workouts in a plan?

Ok, so I must have programed in a training block, before stuff got all redone, and I didn’t notice it until I listened to the podcast where they mention changing everything, and working on the progression levels, etc. I had already started the 2nd week when I realized I could set an earlier start date than the current date, and kind of plug in the new plan.

Anyway, long story short, the old version of the half-distance low volume build plan had some very difficult VO2 sessions to start. Shortoff +1 is a 7.3 level, and Givens is a 9.4. I completed both of those (Givens was extremely difficult, but I didn’t back pedal or take any breaks). Then I looked more closely at the plan and realized that it didn’t really progress to much, looked at the new plan, liked what I saw more, so swapped it out. Now the workouts progress much nicer. But I’m wondering if I should now start plugging in more difficult VO2 workouts for the planned ones? For example, next week I have a 4.3 VO2 workout in the plan. It isn’t going to be “easy” but I wonder if I’m losing something by not continuing to push the VO2 workouts. With the levels, it wouldn’t be hard to find workouts that continue to build off Givens, maybe find a 9.6, 9.8, etc and plug those in. My concern is slogging through these really tough VO2 sessions when I’m trying to build up endurance for a Half distance race that might impact my ability to recover and really hit the other key sessions.

Ideas? Thanks in advance.