in my experience switch does a pretty good job at balancing the load. Typically your host will be "pinned" to one of the ISLs and if that links goes down your host will notice it because its connection will be "re-pinned" to another ISL. When you use port-channels your host would never experience any disruption in service because port-channel state does not change when member links go up or down.
Hello,  I have multiple ISL links between my edge and core switches. These links are not channeled together to form one large pipe. Do I really need to channel them? Doesn't the switch balance the load between ISLs anyway?  Thanks.
Port Channeling ISLs