The phrase "used whenever needed" is correct and usable in written English.
It can be used to indicate that something is available for use at any time it is required.
Example: "The emergency kit is designed to be used whenever needed during a crisis."
Alternatives: "utilized as necessary" or "employed when required".
We're just trying to catch up, since they've shown that it should be used whenever needed".
Interpreters are used whenever needed during assessments, and will be present during all assessment and treatment sessions for children who are not fluent in Finnish.
Conversely, for equipment that is less expensive to purchase and operate, it may be more cost-effective to buy many units, so that they can readily be used whenever needed, even if they are not constantly in use.
If making rasam very rarely, store the rasam powder in the freezer and use whenever needed.
Although many units that are collected are later discarded, because they test positive for certain diseases or are too small to be of use, the blood found suitable can be stored for use whenever needed, with no need for further involvement by the donor.
Originally, the concept was to offer consumers a small, portable Wi-Fi hotspot that could be used whenever you needed connectivity.
"Or, maybe worse, that he sees foreign and security policy as a game to be used whenever he needs distractions for domestic political purposes".
Under a subscription model, individuals would pay a flat fee on a monthly or annual basis for unlimited access to a given fleet of vehicles, to be used whenever they need a ride — loosely analogous to a SaaS model.
Furthermore, cryopreservation has the advantage that the cells can be used, whenever they are needed.
Routine haematoxylin eosin staining was used on cell-block sections, and IHC was used whenever this was needed for tumor origin identification.
Semi-parallel, or folded, VLSI architectures are used whenever hardware resources need to be saved.
