You get three attempts at the snatch and three at the clean and jerk. Your total is your best successful snatch plus your best successful clean and jerk. Nothing else counts, and a missed lift is worth exactly zero.
Miss all three snatches and you have no total at all. Not a small total. None. The clean and jerks still happen, they simply do not add up to anything, and you spend the second half of a competition lifting for nothing. That is the fact the whole strategy comes out of, and it is why weightlifting openers are chosen more carefully than powerlifting ones.
The snatch is not like the clean and jerk
It is the more technical lift, it is the one that punishes a millimetre, and it comes first. A snatch that is 4kg too ambitious does not just cost you 4kg. It can cost you the competition before the second half begins.
So the two halves of the day are not symmetrical and should not be planned as though they are. Open the snatch to guarantee a total. Open the clean and jerk to build one.
The opener is the most important lift of the day
It is the weight you could hit on the worst day of your life, in front of a crowd, after a weigh-in that did not go to plan. If there is any doubt at all, it is too heavy.
Missing an opener does not just cost you one attempt. It costs you the next two, because now you are chasing and every decision after it is made in a panic. A conservative opener buys you the whole rest of the day.
The second is where the total is made
This is the one that should be a small, confident step. Something you have done in training, or very close to it. Most totals are made here, not on the third.
If the opener flew, you can stretch it slightly. If it felt heavy, do not pretend otherwise. The bar does not care what you had written down that morning.
The third is the one you can afford to miss
By now you have a total in the bank and you know how the day is going. This is the attempt that can be a genuine personal best, because missing it costs you nothing you had already banked.
The exception is a qualifying total or a placing. Then the third is arithmetic, not ambition: it is whatever number you need, and if that number is out of reach the honest move is to take something you will make and finish with a total.
Jumps, and the 1kg step
An IWF platform loads in 1kg steps, so weightlifting attempts do not round the way powerlifting ones do. That is a finer grid than most lifters use, and it is worth using: a 2kg jump is a real jump in a sport where the difference between a make and a miss is often a hand's width of bar path.
The weightlifting attempt calculator will work openers, seconds and thirds out for both lifts, with the warm-up ramp and the plate loading already done.
Do not build attempts on a calculated max
A calculated one rep max is a guess with decimal places. Attempts built on a guess are a guess you have to make in front of three judges.
If you do not have a recent single on a lift, use the heaviest clean triple you have done and put that in instead. You will get a conservative frame, which is the right error to make.
The short version
Open where you cannot miss, especially in the snatch. Make the total on the second. Spend the third on something you actually want, unless a qualifying total says otherwise. And decide all six weeks out, not in the warm-up room.
Attempts are the last two percent of a meet. The twelve weeks before them decide what you are opening on, and that is the half a calculator cannot do for you.