- When they face a larger force and have to pick off individuals.
- To spy on meetings and events
- To get into attack position usually by negotiating a path through a visible region
- To get to a position where they can trigger certain key attacks/abilities
To be useful Sneak needs to allow you to stay in position for long periods of time without detection and to be able to move within reason through a crowd to get to a particular target.
My understanding is that the new sneak system once another player/npc turns in your direction there is an increasing likelyhood of being detected with time (atm way too easily). The ability to wait and plan has gone, the ability to spy has gone. Time should not be a factor in staying sneaked if all other variables remain the same.
The sneak system I think should reward and encourage sneaky play, when you are stationary you should get a significant sneak bonus, when you move sneak should take a penalty (ideally with move speed a factor though I realise that is probably asking too much). We need to factility to be able to wait our chance, to remain cloaked until the strike is possible or until a viable path is able to be negotiated.
Detection in sneak should not break you from sneak mode, a player observing a sneaked character may indeed have a reason to allow them to go about their business, may be luring them into a trap etc strategy can be used...sneak should only break when an attack is made on that character (whether it hits or not it hits it should still break sneak).
Certain attacks should leave the player in sneak for a follow up....perhaps for a period of time during the attack and just after the ability of the sneaked charater to be detected should be increased, this promotes cleaver positioning and again rewards player strategy.
In a similar manner lets reward and encourage clever detection techiniques, a players ability to detect a stealthed chracter should depend on how they are behaving when running or in combat the ability to detect should be penalised, standing it should be average and walking (ie a style of searching) should get a detection bonus......again give the player an ability to be involved in making the difference.
In summary rather that have time a factor in detecting a sneaked character, vary the 'ability to stay sneaked' based on the action being taken, vary the ability to detect in a simialr manner - give the players the ability to make the distinction and to use skill and guile take the rewards or else suffer the consequeces....this is after all what spying is all about 
) Sneak is a huge aspect of pvp, especially for vector, and ESPECIALLY for Exiles. We can't fight the zerg, but hell, we should be able to stick a knife in their face or give'em a nice kick in the nuts every once in a while!
