The phrase "a very laborious" is correct and usable in written English.
It can be used to describe a task or process that requires a lot of effort and hard work.
Example: "The project turned out to be a very laborious undertaking, requiring countless hours of research and development."
Alternatives: "an extremely arduous" or "a highly demanding".
I make for my family, but it's a very laborious dish".
"It was a very laborious and arduous process, but we have done everything by the book," Mr. Pace said.
"One of the very difficult problems presented when people commit criminal acts like this is that you have to go through a very laborious process of tracking everything back," said one agency official involved in the matter.
"It's a very laborious process, and there a lot of hoops to jump through," said Mr. Gray, who began his fifth venture, the Gung Ho! Gourmet Pizza Factory delivery service, with a fellow New Zealander a year ago.
But it not only required the custom built "smart" badges, it also required a very laborious infrastructure, with an infrared receiver located in every room of the building.
"It was a very laborious process that took over two months to complete from beginning to end… but was completely worth it".
Since column transport experiments are very laborious, a common alternative is to perform batch experiments where usually one or two measurements are done assuming equilibrium is reached.
Always a mathematical challenge and very laborious.
The process for obtaining monoclonal antibodies against a specific antigen is very laborious, involves sophisticated technologies and it is not available in most research laboratories.
Ducts can be seen entering, branching within and leaving a thick section, so it is possible to follow the ramifications of all ducts throughout a whole breast, but very laborious to do so by manual methods.
