Hi @katiebroyles,
I have done something very similar to this for one of my clients before. It was weighted distributions of tickets, instead of new leads, but the principle should be the same. From my understanding of HubSpot workflows, the only options are to rotate the record to a user or a team. As neither of these did what we needed, we were able to use Operations Hub’s Custom Code Actions in workflows to distribute the ticket. This was done by keeping a store of past ticketing assignments and making sure the next ticketing assignment was done according to the previous ones. Since we were using Custom Code for this, it was even possible to change the distribution weights based on how many tickets each CSR had at the time of assignment.
Now without Operations Hub(or third party integrations like Zapier or Integromat), and if it weren’t for the exact percentages you chose it wouldn’t be possible to my understanding, but I’d be glad if someone could show me how to do this with precision using just built-in HubSpot features. But, because you have 3 users and you’d like to do 45% 45%, and 10% it is possible, though not very clean. If you have a Sales Hub Professional or Enterprise or Service Hub Professional or Enterprise account, you can rotate assignments between multiple users using workflows. So theoretically you could rotate between the 3 owners, then if the owner was that third person, rotate the record again between those 3 owners. This would result in percentages of 4/9(44.44%) and 4/9(44.44%) and 1/9(11.11%).
This is obviously not very practical in the long run of a growing business though, so I would recommend using Operations Hub or some third party integration that allows you more programmatic control.