1 1/2 hours per pound is for 225F grate temp, unwrapped. I'm not sure what your grate temp was. Also, a UDS is so efficient that you don't have to keep opening it to add fuel. Each time you open a smoker you add time to the cook.
Jim - Another transplanted Texan
Former KCBS CBJ
Large and Medium Big Green Eggs , Black 18.5" WSM, Blue Weber Performer - Stainless, Green Weber OTG Kettle , Brinkmann SnP Pro, and a Stainless UDS. One retired Portable Kitchen grill.
Red Thermapen, Maverick ET-732, EdgePro Apex Sharpener.
Avatar is the original 1951 Weber Kettle