displaying hard work and attention to detail
assiduous - careful
If you are ‘assiduous’, then you take great care over something that you do, and do it with persistence and patience. For that reason, this word is most commonly used in a professional context and in a highly positive way.
Thanks to assiduous planning, the project was completed without any delays or setbacks.
Mary is an assiduous student. I think she will ease through her exams.
The new government has followed through on their election promises with commendable assiduity.