Unless we think they’d be doing something particularly valuable with that lost time, I probably wouldn’t. That these people are signing up at all is a sign that they do care about others significantly, but it’s not a sign that they care about cost-effectiveness.
EDIT: Also, you have approximately 0 effect on whether the others choose to sign up, so you have no control over these opportunity costs.
Unless we think they’d be doing something particularly valuable with that lost time, I probably wouldn’t. That these people are signing up at all is a sign that they do care about others significantly, but it’s not a sign that they care about cost-effectiveness.
EDIT: Also, you have approximately 0 effect on whether the others choose to sign up, so you have no control over these opportunity costs.