Furthermore, the intervals E-A/A-D/D-G and B-E are not exactly perfect fourths, they should be equal tempered. Luckily the difference is almost negligible for the fourth, the perfect interval would be 4/3 = 1.3333 versus 2^(5/12) = 1.3348 for equal temperament. The interval G-B however is a major third, here the perfect interval is 5/4 = 1.25 while equal tempered is 2^(4/12) = 1.26 Those minor errors accumulate if one string is tuned based on the preceding one, the interval from lowest to highest strings can be calculated:
(4/3)^4 * 5/4 = 3.95 for perfect intervals, 2^(4 * 5/12) * 2^(4/12) = 4 for equal temperament.
The highest string should be exactly two octaves (= a factor of 4) above the lowest one, so the equal temperament should be preferred. A practical result is that tuning a guitar using only intervals of adjacent strings will never really converge to the ideal result, so tuning (fretted) octaves and flageolets should be used in addition.