Constant or persistent in use or attention; persevering in effort.
Synonyms are 'assiduous' and 'diligent'; of the three, 'sedulous' is probably the least common in modern use.
Etymology: 1500s, Latin sedulus, "attentive, painstaking", which apparently came from sedolo (se, without + dolo, guile).
"...after a drake of the beautiful mandarin teal had been stolen, the duck remained disconsolate, though sedulously courted by another mandarin drake, who displayed before her all his charms. After an interval of three weeks the stolen drake was recovered, and instantly the pair recognised each other with extreme joy. On the other hand, starlings, as we have seen, may be consoled thrice in the same day for the loss of their mates." - Charles Darwin, "The Descent of Man"
My sedulous study of the design documents only served to reveal more and more gaps in the consultants' solution.