A shared device can serve different tasks and reduce the need for separate purchases. Its usefulness depends on the distribution of uses and labor conditions. Sufficient availability on average may be inadequate when more people need it at the same time.
I propose to reconstruct the frequency, duration and constraints of the activities. Sharing must include access to and processing of appropriate information. Moving and configuring can also take time: these steps should be included in the comparison, avoiding to consider only the cost of purchase avoided.
In a hypothetical example, a tablet is used for inventory and customer service. If the two activities coincide during the opening, sharing can create waits. A calendar or a different organization may be workable, but it requires field verification.
The test should observe usage and interruptions. The environmental benefit cannot be inferred automatically from the number of devices. Sharing is a useful choice when it enables reliable service and makes resource use more efficient without producing disproportionate difficulties for those who work.