You read that right - but let me explain:
While in-game, after hours of experimenting, I found that the fuel burn is lower (range longer) at almost all weights, altitudes, and speeds with 1-5 degrees of flaps. This is in fact realistic, and accurate because:
In real life, 787 has electronically actuated variable trailing edge camber which is “completely transparent to the flight crew”. This was not re-created in IF’s 787 - so it is not completely transparent to the pilot - but must be manually controlled by the pilot to mirror something similar to what would be happening in real life.
After diving into the World Wide Web, and digging through presentations, articles, and academic papers: here are the best 3 sources I have found to explain the use of flaps in cruise on the 787
Boeing’s chief aerodynamicist in 2011 created this presentation. Please reference page 17
The Next Decade in Commerical Aviation Aerodynamics
Green Aviation: Green Aviation
Google Book so I’ve taken screenshots for those who wouldn’t have access
In summary - while a pilot selecting certain degrees of flaps while in cruise is unrealistic - the actual effect is similar to what would be occurring in real life with some minor extension of the trailing edge flaps by the flight system. The biggest difference being that the slats on the leading edge would not change position.