Problems and pain points with Lead-Gen

Disclaimer: Im not trying to sell anything here and I know doing it would be against the subreddit rules. I just want to do research in order to improve my service.

Background: I sold commercial insurance to contractors and tradespeople for about two years in germany. Mostly through cold calling, 100-150 dials a day, the usual grind.
At the beginning, most guys never picked up and the ones who did were on a job site and pissed that I was calling. I eventually got better at calling over time, but the pain of doing it constantly was too much for me to carry on.
A few of my colleagues, who were longer in the game, hired freelancers to make cold calls for them, but that didn't always work and was really expensive.

I'm working on a cold email lead gen service for insurance agents and eventually want to offer it in the US (Again, no pitching). But before I do anything I want to actually understand how prospecting/lead-gen works for you guys because I know the US market is a bit different to the german.

So my questions for anyone writing commercial lines: Do you deal with the same stuff I described or are the pain points totally different over here?

And if you were to hire a service provider to help you generate leads, what would you expect from the partnership in terms of amount of leads generated per month etc.? I’d also appreciate hearing about your experiences (good and bad) with service providers you’ve hired in the past.