I agree entirely Pilotchute, my last job had exactly the same problem. I had a twin dangled infront of me and was happy to stick around for it, when it finally came time everything was very drawn out, I was unable to get the ICUS time to meet insurance minimums because I was too busy flying the Singles as a bunch of people left when they hit that roof and then when I finally did get it all sorted (Almost 3 months after my endorsement!!) there wasn't a lot of work around for it and the next step up was denied me because of being on the Twin (another story, don't ask!).
I was thinking the exact same thing myself, you see all these ads for "Senior Pilots" which becomes a bit worrying when you consider if its because the company simply isn't doing anything to encourage retention of staff, expansion beyond their current staff members experience or it was just simply people moving on.