Kubernates pods with :latest Image issue

If the image tag is the same in both apply and set image then only the apply action re-deploy the Deployment (in which case you do not need the set image command). If they refer to different image tags then yes, the deployment will be run twice.

If you use latest tag, applying a manifest that use the latest tag with no modification WILL NOT re-deploy the Deployment. You need to introduce a modification to the manifest file in order to force Kubernetes to re-deploy. Like for my case, I use date command to generate a TIMESTAMP variable that is passed as in the env spec of the pod container which my container does not use in any way, just to force a re-deploy of the Deployment. Or you can also use kubectl rollout restart deployment/name if you are using Kubernetes 1.15 or later.

Other than wasted bandwidth or if you are being charged by how many times you pull a docker image (poor you), there is no harm with additional image pull just to be sure you are using the latest image version. Even if you use a specific image tag with version numbers like 1.10.112-rc5, they will be case where you or your fellow developers forget to update the version number when pushing a modified image version. IMHO, imagePullPolicy=always should be the default rather than explicitly required.