The phrase "a lengthy and difficult" is correct and usable in written English.
It can be used to describe a task, process, or situation that requires a significant amount of time and effort to complete or understand.
Example: "The project turned out to be a lengthy and difficult endeavor, requiring months of research and collaboration."
Alternatives: "a long and challenging" or "an extensive and arduous".
But that will require a lengthy and difficult constitutional reform.
For that to happen, state legislatures and voters would need to revise state constitutions, typically a lengthy and difficult process.
But creating a new culture is a lengthy and difficult undertaking, as the winners of the first season of Mashrouy know all too well.
"Coming to this decision has been a lengthy and difficult process and I am extremely disappointed to have been put in this unfortunate position".
They indicate the extent of the previous problems at the bank and emphasise that the turnaround is a lengthy and difficult process," the bank said.
It is known that the implementation of chemical registration systems can be a lengthy and difficult process.
By early summer 1874, he had completed the work, a lengthy and fiendishly difficult suite for solo piano.
"However we are aware that the consultation has been a lengthy and very difficult one with a number of organisations and individuals in the field arguing that an end to donor anonymity would lead to a shortage of donors.
The UN-CMCoord experts have a lengthy and also difficult task at hand as they sit down and talk to warring parties.
Identification and cloning of genes encoding insecticide target sites composed of multiple subunit proteins (such as the nicotinic acetylcholine receptor) by degenerate PCR is also a lengthy and sometimes difficult process.
The most common treatment for focal dystonia is retraining, an often lengthy and difficult process in which a patient learns new ways of using the affected muscles.
