Source: March 2014 ACBL Bridge Bulletin 
Standard systems, where the opening bid of one of a suit has a wide range — anywhere from 12 to 21 points — contain a built-in headache. The problem comes with opener’s simple change of suit rebid, e.g. 1 -1; 2. Opener may have a relatively balanced minimum, such as:
K 4 97 A Q 8 6 2 K 9 63,
or a genuine two-suiter as strong as: A 4 9 A K 8 6 2 K Q 9 6 3.
The second hand is really not strong enough to jump to 3, which is a game force. True, if opener finds a good fit, 5/5 may be within reach, even opposite a minimum response, but, without a good fit, all game contracts, including 3NT, rate to be too high. And if responder expects a hand of at least 19 points, he will drive to many poor slams. This means that the change-of-suit rebid also has a wide range, about 12-18 points.
How does responder cope with the headache created by this wide range?
The most prudent course is to try to keep the auction alive in case partner’s hand is strong. This necessitates mark-time preferences. Suppose you hold: Q 8 7 3 2 K 6 5 10 3 A 5 2. After 1 -1; 2– ?, the best rebid is 2. True, you prefer clubs to diamonds, so this is a false preference. This sequence also poses challenges for partnerships that routinely open 1 holding five clubs, four diamonds,
minimum values and a hand unsuited for a 1NT bid over partner’s one-of-a-major response.
All other rebids are much more distorted. 2 on a poor five-card suit is asking for trouble. There are a few occasions when rebidding a five-card suit is in order, but this is not one of those times. The hand is too weak for an invitational 2NT, and pass risks missing game when opener is near the top of his range.
2 , the mark-time preference, keeps the ball in play. If opener is minimum, he will pass and remain at the proper level, although perhaps in the second-best trump suit if opener is 5-5 in the minors. When opener is strong enough for a third bid, he can offer three-card support for spades, or bid 2NT with a heart stopper or 3 with a good 5-5. All of these rebids will be welcome news to responder, opening the door to much better contracts than 2 or 2 (if responder had passed). Opener doesn’t have a difficult time with his third bid, as long as he remembers not to rely on diamond support. After all, the sequence is really the country cousin of 1 -1NT; 2 -2, where the 2 preference is most often a doubleton.
Let’s say as dealer you pick up: K 10 5 A K 9 6 4 3 — K Q 8 2. You open 1, partner responds 1. What’s your call?
You could jump to 3, invitational, but you are still within range for a simple 2 rebid. The advantages of 2 are numerous. This hand may play well in hearts, spades, clubs or possibly notrump. By keeping the auction low, you have a good chance you’ll be able to complete the description of this hand.
For instance, suppose partner bids 3. You can continue with 3 to show the sixth heart. If partner next bids 3NT, 4 nicely completes your picture. You will reach 6-2 heart fits and 5-3 spades, or play clubs absent any major-suit fits. If partner rebids 2NT and then 3NT, you can pass with few qualms, once you have indicated a three-suited hand short in diamonds.
If you jump to 3 over 1, what would you do if partner rebids 3NT? Take out to 4? Try 4, hoping partner has five? Pass 3NT and hope for the best? All the choices are awkward guesses.
2 works well most of the time, especially if partner is conditioned to keep the auction open on hands worth 8-10 points. Suppose partner was dealt: A 6 4 2 9 5 J 10 8 4 A 7 3 and sees the auction 1 -1; 2 -? The mark-time preference, 2 , is the ticket. It doesn’t overstate the hearts and avoids overbidding with 2NT or underbidding by passing and perhaps playing the wrong partial, especially at matchpoints. Standard systems create this recur-ring rebid headache, but there is a panacea. Take a good dose of mark-time before bedtime.