Not so common, more like silly mistakes.

1.In a recently played match, I had the following tenpai:

Dora: 6m (Hatsu was pon'd)

Nothing special, it's a tenpai waiting on 78m.

Then I drew 4m.

It's either 4666m with 45m wait or 6668 with 78m wait. Better discard 4m since waiting on 78m should be a little bit easier to win on...

Wait, what...

I failed to realize that had I discarded 8m, I would have waited on 145m!

2.In another recent match, I had the following tenpai:

Dora: 9p. (9p and haku were pon'd)

Haneman tenpai. Opposite player declared riichi, but naturally I wanted to play this hand to the end.

On the third to last turn, I drew 1p.

What do I do now? One 1p and one 2p was on the table. Since 1p is one-chance, it should be safer. Let's go.

Uh..........

Not again..........

Should have gone with 2p to get the 145p wait! In his last turn, the riichi player drew 1p to put salt in the wound.

****************************************

If I was given the 1234666p shape, I would realize right away that this shape is waiting on 145p. But somehow, in these two different situations leading to that shape, I managed to make two different mistakes in similar fashion. Wow...

It's so easy to make careless mistakes. That's why it's important to pay attention to every detail. Or you could make the mistakes several times and then eventually remember it. Like me.

I really hate myself sometimes.