General:
* Leave no stone unturned: This classic idiom means to search everywhere and consider every possibility.
* Go the extra mile: This idiom signifies exceeding expectations and putting in extra effort to ensure thoroughness.
* Be meticulous: This simply means paying close attention to detail and being careful in every step.
* Be painstaking: This implies taking great care and effort, even if the task is tedious.
* Be exhaustive: This describes a thorough search or examination that covers everything.
Specific to tasks:
* Comb through: This means to examine something carefully and completely, like combing through hair.
* Scrutinize: This implies examining something closely and critically.
* Pore over: This describes studying something very carefully, often line by line.
* Drill down: This suggests investigating something in great detail, getting to the root of the matter.
The best idiom to use will depend on the specific context.