One of the most frequent “bridge crimes” is the leap to 4 of a major on any type of hand. Certainly it pre-empts the opponents but it takes partner along with them . If you have no respect for partner, continue to leap to 4/ with any kind of hand . The immediate jump to game should be a pre-empt – nothing more , nothing less . What do you do with distributional hands that are slightly better then a pre-empt and with length in trump so you want to leap to game ?
There are many ways to handle these hands . First a rule . A leap to game shows no outside controls or an outside useful suit, period . If you choose to splinter then you should have defense with these kind of hands otherwise just leap to game . If you have an outside suit and not overly strong , I like the Cabay “flower treatment” or fit showing jump . xxxxx x KQJ10x xx . Leap to 4 after a spade opener !! Showing a void in the era of Exclusion Blackwood is archaic. By bidding 4 and “showing where you live” as Kiz would call it , has two great advantages. You help partner in competition if the opponents bid again and you assist in slam bidding . AKxxx Axx xxxx A and you are cold for 6 after a 4 bid . If the opponents interfere you probably would bid again with your diamond length.
O.K. how do you bid a leap to 4 of a major with outside controls . Say you have xxxxxx Ax Ax xxx and partner opens 1 . You would like to leap to 4 but you are way too strong .Tom & I have adjusted our 2NT downward so we can bid 2NT with this hand. In competition you may get away with a jump to game. There is a rule “do not pre-empt over a pre-empt”. So if the auction goes 1-3-4-P partner will play you for values.
There should be some simple rules for the fit showing jump at the four level. It should only occur with the minors as 1-P-4 is to play as is 1-P-4.
Splinters in competition are a losing proposition. They violate the principle of concealment and just help the opponents with their opening lead or competitive decisions. The tactical advantage of a leap to game is “keep them guessing” . The inference that you did not make a fit showing jump means that your values are just in trump and further defines that bid. You most likely have a singleton or void somewhere but let them find out when they view the dummy. Even as a passed hand you should not leap to game with values or if partner overcalls. The bid is a pre-empt in all these situations. You can always choose a better bid to describe a hand that might make game in your partners major.
Since we have the bases covered with a splinter , a flower bid and a 2NT jump there is no excuse for the ambiguous 4/ jump . If you do jump to game partner will know in competitive situations that you do not have a good suit to contribute or outside controls . Leaping to game is no longer a crap shoot leaving everybody ( including partner ) in the dark. These treatments can work as a passed hand , with overcalls and over takeout doubles.