I have always had very good experiences with the lawyers/paralegals on my cases. True they tend to take time but I attribute that to 3 reasons
1. Volume of work
2. Batch processing
3. Extra due diligence (I have Fragomen and they had some issues a few yrs back).
I feel like a little better work upfront will minimize the risk of RFEs later so I don't mind if it's reason#3.