Is time a resource?

Yes. Reminds me of the quote "time is money".

Definitely. However, different cultures handle this resource in different ways. See the sites below.

http://www.members.cox.net/dagershaw/lol/MexicanClock.html
http://www.members.cox.net/dagershaw/lol/PastPresentFuture.html

I hope this helps a little more. Thanks for asking.

In my management activities, time was usually a constraint. Some folks consider constraints to be limited resources, so it that sense it is a resource.

Yes, time can be considered as a resource in the context of management activities. When managing projects or tasks, time is often a constraint and needs to be allocated effectively. Just like any other limited resource, it needs to be managed and prioritized to ensure maximum efficiency and productivity. In this sense, time can be seen as a valuable resource that needs to be carefully managed and utilized.