"I removed myself as an auth user on friend’s Cap1 card in February because it was hurting me more than helping and my score jumped up to 652 in April, which was surprising to me."
Just as an aside, one quick thought here Sir... I suspect the 90% utilization was the issue, as level of debt/credit utilization is a 23 - 30% factor influencing your score.
So while there's a theoretical hit from removing the length of credit/credit history from your score (but removing the account from consideration), it was clearly offset (and then some) by the reduction in utilization!
