I always try one at 13 yards to see if the POA and POI is where it should be. Then I'll shoot 2 shells at 35 yards with an IM choke and 2 with a full choke. Then average the pellet count for each choke. Besides pellet count, I'm also looking for holes in the patteren, not good. I always use a rest. Wayne
I just shoot standard stuff (name-brand wads, popular powder, 209A primers in any hull) and it always works. And when I pattern it, it's little if any different from the last ones I patterned. OK, Green Dot was a bit tighter than Red dot, but that about covers it. If it sounds OK, it is OK in my book. I'll soon be posting a wad test with 7/8 oz. loads which illustrates my point.
I will usually pattern a new load if for nothing else, my confidence in the load. I then shoot the load for a season, or at least 5,000 registered birds. If I am having problems with my scores, I might change loads. The shell is most likely not the cause of my problems but it is the easiest thing to change. The mental part of shooting trap is important.
I usually run some over a chronograph and do some patterns. I also put some in the freezer and give them a try over the chronograph again while they are still cold. It gives me a rough idea of what to expect in colder weather. Some loads will pattern well in some guns and be dismal in another. It's a crap shoot. I will say one thing though, when you look at patterns and count pellets and spend all of that time, it sometimes has little to do with how well you will do with them. It has EVERYTHING to do with your confidence in the load. Maybe that's a big difference for some.
For your original question, I load about two to four boxes for chronographing and patterning, depending on how many pellet holes I'm in the mood to count. I then load about four more boxes and shoot some at targets and see how they work. I'll know if I like them by the time I get through a flat.
Put a Winchester W209 primer in that load you posted and you have a winner! It's worked VERY well for me at handicap. If I miss one, it's not the gun or the load. It goes about 1230 fps out of an IC choke in my 1100 at around 75 degrees. They still go around 1185 when the temps go down to under 20 and still sound solid. 85 - 90 Degree weather and a Full choke puts them up near 1260 over my chronograph. Drop the powder about a grain or a little less and you have a good 16 yard load. Any lighter and I'd be using Red Dot or Promo instead.
I did not play around with to many different loads in my short reloading life thus far, but when I did change. I would load up 25 shoot a round. If I stayed with in my average. I would try another batch. If I liked them I would spend time on the paper just to be sure they are doing well. I have come to rest with clays powder,1oz shot,remTGT12s wads,STS or CCI primers. runs about 1135fps. so far good back to 25y line.
I'm with shot410ga and Quack. W209 primers with 20 Green Dot in an STS hull with a Fig-8 wad and 1 1/8oz hard shot is a match made in heaven. Drop the powder to 19.1 gr and you have a superb singles and short range handicap load.
Patterning done right is tedious. If I'm trying wads and components I haven't used before, I load up 25 and go shoot. Usually I load up 100. If it smokes them at the range. The only time I'll pattern a test load is if it behaves abnormally at the range. I also chrono my loads. If a new load smokes birds and gives me single digit SDs, I'm happy.