"essential in reaching" is correct and usable in written English.
You can use it when you are talking about something that is necessary to achieve a goal or outcome. For example, "Gathering feedback from customers is essential in reaching a successful decision."
Community-based co-design was essential in reaching this result.
The design of new excipients that extend the release of drugs from tablets over prolonged periods is essential in reaching enhanced therapeutic performances.
The quality and interpretation, preferably by a paediatric radiologist, of radiographs is essential in reaching a correct diagnosis in cases of suspected child abuse.
Use of extensive temporal RNA-seq data in combination with computational predictions and Northern-based assays are essential in reaching robust outcomes in identifying previously unexplored sRNAs.
Such approaches are essential in reaching the most isolated or excluded, and they can also foster community ownership of health programmes, stimulate demand for quality health services from governments and add vitality to a bureaucracy-laden health system.
This led to a debate within the PT department whether or not the extra time investment should be maintained, i.e. whether the second daily visit was essential in reaching the short-term PT goals and whether having only one session of PT a day would lead to poorer range of motion (ROM) and function.
Cities are responsible for roughly two-thirds of global primary energy consumption, and are therefore expected to play an essential role in reaching European climate change targets.
Bioenergy should play an essential part in reaching targets to replace petroleum-based transportation fuels with a viable alternative, and in reducing long-term carbon dioxide emissions, if environmental and economic sustainability are considered carefully.
Such delays may be due to delay in seeking essential obstetric care; in reaching the hospital or appropriate health facility; or in receiving adequate care in the hospital [ 8].
Third-year students' more frequent use of textbooks may reflect the development of their ability in reaching essential resources.
In reaching a decision, it is essential to take the consequences of the different alternatives into consideration.
