Which are your key sessions in your training week?

Hi all

I’m currently training for my first IM 70.3 in June. My typical training week consists of 8 sessions spread over 6 days (+1 recovery day). There are two swims, two bike workouts, two runs and two strength/mobility sessions.

Within each discipline I usually plan a longer aerobic endurance session and a speed workout with shorter intervals at higher intensities.

As life sometimes goes, not every week is perfect and sometimes I have to skip certain sessions. My question is: Which sessions/workouts within the three disciplines are your key sessions and which ones would you skip first? E.g. would you rather skip the long run or the interval session?

I’m curious to hear your opinion!