Hi @BenjaminBlackshear
There is an excellent post on this topic here that is well worth a read.
https://community.esri.com/community/implementing-arcgis/blog/2020/04/30/planning-load-balancer-conf...
In a nutshell, you need a HealthCheck for each target (VIP) endpoint configured with the Load Balancer. If there are Web Adaptors, you only need to check that the Web Adaptors are available.
In your setup, with Portal & Server Web Adaptors on the same machine, I guess you have LB set to share all incoming requests to one "target group" with two Machines.
In that case, you only really need a tcp availability health check for the Web Server hosting the two Web Adaptors. You do not need to use the Portal or Server healthCheck REST endpoints. (The Web Adaptors use these behind the scenes).
If you use separate targets for the portal and server Web Adaptors, you could try just simple html checks for the healthCheck addresses. But... this only tells the Load Balancer that the Web Adaptor on that machine is working and that at least one of the portal/server sites is responding ok. The healthCheck endpoints are not always super fast to respond, so allow some more time and a few more retries than you may expect (as per the blog article)
Hope this helps