Estimation is an important skill to have and I have been working on it. After every board, I estimate whether the board is a top (+2), a bottom (-2) or in between. Because you have about 25 boards in a session, adding these scores can give a pretty good estimate of how you are faring. Of course, it works only if your estimates (-2 to 2) are reasonable.
So, I went back and looked to see where and why my estimates were off. In general, lots of boards I had marked as average (0) turned out to be Average+ (about 8 out of 12). Essentially, getting to the right contract was worth an Average+. Theoretically these ought to get washed out by boards where the opponents got to the right contract their way. Even though I consistently marked those also as average (0), they too turned out to be Average+ because the field was not taking all their tricks on defense. Similarly, I would mark down a board where we dropped a trick as below average (-1) but it would turn out that the field was not picking up these tricks either.
Turns out that many of the stronger players were playing the first round of knockouts. It may have been an "open pairs", but the field was relatively weak.
The only true mishap of the day occurred on a board where I made two bad decisions in the bidding:
I was West and had to decide whether to open this hand 1H or 1NT. With a 15-17 balanced hand, I always open 1NT even if I have a 5-card major. However, I decided to upgrade the hand, open 1H and rebid 2NT. That was mistake #1. This is pretty clearly not an upgradeable hand. Partner now bid 1NT (semi-forcing) and South overcalled 2S. What's my bid now?
I doubled (takeout) and partner bid 3C. This is where mistake #2 happened. Forgetting that I had doubled (so 3C was to play), I bid 3S and put partner in a hopeless 3NT contract. That was our only zero of the night. Had I passed 3C on this board, we might have won the overalls too, not just the E/W direction, because 3C making 4 would have been Average+.
But I should not complain too much -- the other bidding misunderstanding of the night gave us a cold top (all 12 of the matchpoints). It was on this board:
After North passed, partner (East) opened 1D and South overcalled 2S (weak). I bid 3S.
Now, partner had a problem. Was my 3S a limit raise of diamonds or a general-purpose force where his first priority is to bid 3NT with a spade stopper? In any case, he had no spade stopper, so he bid 4D. Back to me. Well, if partner doesn't have a spade stopper, I can see a diamond slam if partner has a spade singleton. So, I cue-bid 4H. Would partner cue-bid 4S?
Partner was not on the same page, however. Was 4H a cue-bid with diamonds agreed, or an offer to play? Partner passed my 4H bid. Oops.
The Ace of spades was led and dummy came down. What do you do?
"Thank you, partner," I said. No one needed to know that I was in a 4-2 fit.
Ace of spades was followed by a low spade to South's Jack. South then switched to his Q of diamonds. No surprise there. Diamonds were 2-1 with the preemptor having only one diamond. Chances were that his heart and club holdings were then 3-3.
Who rates to have the Queen of hearts? North, of course. Firstly, he has 4 hearts to South's three. Secondly, with the KQJ of spades and Qxx of hearts, South would probably bid 1S, not 2S. So, I took the diamond switch in hand, and played Ace of hearts and the Jack.
North didn't cover the Jack and I was home. I ran the Jack, played a club to the Ace, pulled a round of trumps with the king and started running my diamonds. North could ruff in with the Queen of hearts, but I had the rest.
4H made on the 4-2 fit was a cold top. The better pairs were in 5D while the rest of the field were in diamond part-scores or failing in 3NT.