I do a lot like Broz does. For one thing, I never load test when the wind is blowing and I always test at 300 yards. I'm talking about a dedicated long range rig and not some short range, lightweight setup which might get by with 100 yard testing.
To my way of thinking, 100 yards leaves too much to the imagination. Small variations tend to get overlooked by people when shooting and testing at 100 yards. When shooting at 300 yards it's more indicative of what the load will do and gives me a far better idea as to whether I want to take it on out to 500, 800 and 1000 plus. I can put as many as 6 to 12 separate bulls on a single sheet of paper on my stand at 300 yards and everything is shot over a Oehler 35P and all field conditions are logged for every shot. Beside each load listing on my loading sheet is a small diagram of the bulls on the sheet and which one is for which load so there's no mixup when going to the target. Also at 300 I can easily spot my shots with the spotting scope.
I will typically load up 2 or 3 extra of the lowest powered load I'm trying and always have a separate target slightly off to the side so I get zeroed before beginning with the testing on the main target sheet. The only time I'll shoot at 100 yards would be if I'm testing a load that is so far different from what I normally shoot that I'm not sure where it's going to print. This is also where the 2 or 3 extra rounds come in handy. I always shoot 3 shot groups for testing but if I find a hummer load then I'll take it out farther and do some final testing with 5 just to satisfy my feeble little mind.
This kind of thing can take time if you're just shooting one gun so always take along 2 or 3 extra big guns and also a .22 and a pistol or two to play with while you're letting your barrel cool. Even better yet is to take a buddy or two along and get everybody in on the shooting. Taken along some milk jugs filled with water, some steel to shoot and even some clay pigeons and you can have a great day.
For the same reason that I'd never shoot a ladder test at 100 yards, I never load test at less than 300 yards. This doesn't mean that it doesn't work for others it's just that I can tell 10 times more what a load is doing at 300 than at 100.
YMMV and that's good, but realistically, why would you test a heavy for caliber, high BC round at 100 yards? You will find that between 100 yards and 300 yards these types of bullets might react differently than you would think. Very very seldom is it that a load that shoots bug holes at 300 won't continue doing the same when you stretch it on out but I've seen loads that showed promise when somebody shot them at 100 yards go in the toilet when shot at 300 on out. For me anyway, testing at 300 saves me a lot of time and barrel life.