I used to think the same way, that a spooked deer would ruin the day. That was until one morning about 5 years back I shot low and missed a 4 point at 12 yards. As upset as I was at such a terrible miss, I kept my compsure and waited to see what would happen. The buck spooked a bit, trotted back about 15 yards and then to my surprise, came back to the previous spot and actually sniffed my arrow which was exposed about mid shaft back. I fired another arrow and unbelieveably missed low again. The buck spooked again, trotted back about 15 yards and again came back to the spot of the two missed shots. As I drew for a third time, Murphy reared his ugly head and the plastic tubing on my peep sight broke with a loud snap. That deer thought enough was enough and broke out at a full run over the ridge and out of sight. This entire encounter lasted about 10 minutes grand total ( although it felt like years). This was only about 730am and I assumed my hunt was done for the day. I was able to rig my peep sight to an operational level and stayed on stand lamenting my poor shooting. As I did a doe and some fawns entered the area. I watched those deer for about an hour when two more does entered the area.From there a steady flow of deer came and went (none presenting a shot) until 1145 that morning.
I learned a few things that day, too much practice is never enough (especially from a treestand), plastic tubing on peep sights can be a liability if not maintained properly, a spooked deer doesnt ruin a hunt necessarily, and even though I felt like crap for missing such an easy opportunity, watching those deer in and out reminded me why I am so damn happy to be in the deer woods on even the worst of days.