Greetings M. Steve,
One piece of good quality seamless gutter will have a hard time going up and down in 120'.
Roof hangers or bar hangers are preferable but spikes and farrels will work as well as long as they hit the rafter ends.
Remember, this is a job in progress, and I would be willing to bet that this job was sub-contracted. As long as she has a warranty on the workmanship, she should be alright.
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