I swear by a Harris bi-pod mounted to my rifle and have used it on nearly every rifle hunt for the past 25 years. In most cases it provides a solid rest. There are some situations however that it just won't cut it. One such case was back in 1995, I drew one of the best deer tags in Nevada. The area I was hunting was filled with waist high sage and gentle rolling hills so it was difficult to find a place for a prone shot. I got into situations where I was trying to rest across some flimsy sage, and a couple very nice bucks I had easy shots on got away.
Then in 2005 in Colorado I had a 3rd season Gunnison basin tag. Some elk hunters blew a 185-190 class buck out of the timber into the sage (sage again) and I made a fast stalk up to a tiny knoll and took a prone rest with a Harris bipod. Everything looked great. The shot was solid and I was close enough that the buck looked as big as a truck in my scope but I missed. The only thing that makes any sense is I clipped some sage near where I was shooting.
The last few years I have succumbed to packing the weight of a solid tripod (Manfrotto) for glassing since it is the only tool I have found that I can glass well from in windy conditions, which is the norm in most of the places we hunt. We have now taken several animals shooting from this tripod. I take the pan head, turn it up 90° so the handle sticks straight in the air, and rest my rifle in the little "crotch" formed by the handle. A solid tripod makes an excellent shooting rest. You can shoot sitting, kneeling or standing off of this. I got the idea watching Mossback videos years ago. I think my next step in this will be to invest in a high quality carbon fiber tripod or an Outdoorsman tripod. I have thought about shooting sticks, but I am carrying the tripod anyways in areas where I'm doing a lot of long range glassing.
In 2009 we used the tripod for my wife to kill her Oregon ram. The best ram in the area gave us the slip on day 3, just as she was ready to take the shot (for the two seconds the ram was still she said should I shoot, and I had my fingers in my ears waiting for her shot). For the next several days we could not find a ram that was even close to it, but could not relocate that ram. On the 8th day, the next to the last day of the season, we decided to drop into a draw and hike up is and glass some areas we could not see from on top. We found the ram bedded uphill from us. We were in the very bottom of the draw (flat portion) and the sheep had us spotted and pinned down. She had to make a steep uphill shot. She sat down and we adjusted the tripod up quite high so she could get a good rest and she drilled him. There would have been no way to take that shot off the Harris bipod.
The nice thing about using the tripod for these types of shots is I that am already packing it around.