You don't have to select intensive or Bubble Soak all the time because every wash programme has its own tumble speeds, rhythm etc. Its just the dose per wash that might need adjustment if you are washing lightly soiled items or heavily soiled ones. If your clothes are very heavily soiled, its best to set the dose per wash to high and select Bubble Soak for good result. The medium dose per wash is the best in both worlds to be honest.
I guess the idea is that the machine detects the load size and doesn't use too much or too little detergent depending on the weight since the dose per wash adjustment doesn't make a massive change to the amount of detergent dispensed per wash (probably a difference of 2-5ml). About the sensors, my WW11BB944DGHS1 has a turbidity sensor but doesn't use it unless the Auto Optimal Wash+ programme is selected - even then, it only detects the level of soiling in two levels (normal or high).
Intensive is a good option since it adds 10 mins and as a result means more time for the water to heat up. Bubble soak is a bit of a powerful option to select to be honest since it maintains the wash temperature and increases the energy consumption by quite a bit.