Losing Trick Count
Once we find a fit, I go to losing trick count, with the CAVEATS that LTC overvalues 5-4 hands, so count an extra ½ or whole loser for those AND LTC overvalues Qxx. Budak considered Qxx as 2½ to 3 losers; Q10x as 2 to 2½ losers and QJx as 2 losers.
So, simple raise of major shows 9 losers.
Limit raise of major shows 8 losers.
With 7 losers and a fit, force to game.
Yes, Aces are undervalued in the HCP systems, but your hand (♠xxx ♥Axxxxx ♦x ♣A10x) is STILL an 8 loser hand when I overcall a spade. It is only a limit raise.
Also, with opening bidder BEHIND you, he is likely to have Kings, so any finesses I need to take in clubs or hearts are likely to lose.
Overcaller's followups after advancer shows a limit raise
When it goes 1♦ on your left; 1♠ by me; 2♦ by RHO; 3♦ by you (limit raise); DOUBLE by original opener, I have 7 options:
1) Pass—shows weakest hand.
2) Bid game—shows enough for game.
3) Cue bid at 4 level—looking for slam—highly unlikely, but possible.
4) Redouble showing first round control of diamonds—also showing slam interest
5) 4NT (RKC for spades)—highly unlikely but possible.
6) Bid 3♠—shows desire to play 3♠ because I did NOT make game try. Does NOT show extras. Might have an extra trump. Might just want to take up a little more room from opponents. Is a sign off.
7) Bid 3♥. This is a GAME TRY. It is NOT help suit because it is the only suit left between the last bid and signing off in 3 of major. But it IS a game try.
Therefore, rebidding 3 of our major is NOT a game try.
Responder and Opener / Overcaller are identifying their hands as Puny (usually just one bid, Invitational (usually two bids unless meaning can be conveyed with one bid), or Game Forcing.
If Responder bids twice, especially when the second bid is at the 3 level, Opener/Overcaller will assume that Responder has Invitational or Game Forcing values, even as a passed hand. When Opener/Overcaller has a great fit, game is still an option. Therefore, Responder must be very careful to not lead Opener/Overcaller on.
When you had ♠— ♥A109x ♦KJxxxx ♣xxx opposite my weak NT and they overcalled 2♣ (single suit), you are pretty sure that suit is spades. But trying to show BOTH hearts and diamonds is overly aggressive. If I have a good fit (which I did), we can get too high. I believe that hand should just sign off in diamonds with ONE BID. (Systemically for us that is 3♦ which is "Stop" since systems are on over 2♣.)
If you had had the ♥Q, then you would have had an invitational hand and could have shown both suits. Then the game I bid would have been on a double finesse through the overcaller: 75%.