Tip Specialization
Screw-on cue tips allow players to use differently shaped points for different ball situations while still using only one cue. Screw-on tips can be shaped to the player's preference to produce power, introduce english (spin) or to graze the cue ball more gently. What's more, the tips can be preformed so that there's no delay in game play when switching from tip to tip.
Ease of Maintenance
Cues with screw-on tips are more easily maintained than those with glued-on tips. Should there be a problem with a glued-on tip--if it breaks or wears out--the tip must be removed with a knife, the tip of the cue cleaned and sanded, and a new tip glued in place. Only after the process is finished and the glue has dried can the cue be used. In contrast, broken or damaged screw-on tips can be replaced simply by unscrewing the old one and attaching the new.
Cue Damage Prevention
Because a new cue can be quite expensive depending on its brand and style, preventing damage to the cue itself is of prime importance. If the shaft of the cue is cracked or split, the entire cue must be replaced. Screw-on tips help to prevent damage to the cue by absorbing some of the shock of ball strikes, and the metal 'head' of the cue resists damaged far better than a wooden one.
Emergency Tip Replacement
The worst case scenario for any serious billiards player is breaking a cue during the middle of a critical game or tournament. The sudden loss of a personal cue may mean using a "house" cue that's slightly bent or worn from use, and certainly does not have the familiar feel of one's own stick. But tip damage doesn't prevent a player who's using screw-on tips from using his own cue. . .he simply replaces the old tip with a fresh tip and he's right back in the game.