Cue my rant on weights in recipes :-)
Weights in recipes are always wrong for you. Very subtle changes in the way you make the cheese will have large effects on how much weight you need. Never follow the recipe's instructions for weights. While the author may find them useful, you will not (except purely by chance).
Instead, follow Gianaclis Caldwell's advice: Only put as much weight on the cheese so that moisture beads up in the holes of the mold. If it's actively running then you are over pressing. For most cheeses, when you first put it in the mold it is already actively running and so you need *no weight*.
Cheese will drain completely without weight. If you ever make a cheddar, you will see that the cheese is basically completely drained before you put it in the press. The reason for pressing is to "close the rind" -- that is, to make it smooth with no cracks or holes. If you press too hard, you will close the rind too quickly and the cheese will not be able to drain. It will retain whey. The whey will get over sour and your cheese will end up crumbly, wet and/or bitter.
It takes about 2 hours for the cheese to drain enough that you can close the rind. You should be slowly closing the rind with the goal of closing it completely at 2 hours. Not before! You can close it after 2 hours, but as the cheese gets more acidic, it's harder to close the rind. This is why you try to time it to 2 hours.
Flip after 15 minutes. Check to see how the rind is closing. If it looks like it is closing and it's still draining whey, then leave the weight at 0. If not, up it until the mold starts to bead up with whey. Flip again after another 15 minutes. Do the same thing, but look at it closely to see how it's closing.
There are 1 1/2 hours left. Flip every 30 minutes (3 times). Just keep upping the weight if it looks like it's not closing. Otherwise leave it alone. If it's not closed after 2 hours, you can put as much weight as you want on it (thousands of pounds if you want) and close it as quickly as you can. Then leave it in the mold until the acidity hits your target.
This is basically the case for every kind of cheese. The only real exception is cheddar which, as I said, is already basically drained before you press it. In that case you want to start at a lower weight to push the air out of the interior of the cheese and then ramp up the weight. However, generally you can put as much weight on it as you want. The only downside to putting too much weight on it too early is that you will get some mechanical holes in the center.
Once you have made a cheese a number of times, you can keep track of how much weight you use. Then you can just load up that much weight for whatever amount of time and it will probably work out OK for you each time. If you give those numbers to someone else and they follow it, there's a possibility that you have just ruined their cheese :-)
It's my biggest frustration about recipes...
