It depends on time and volatility. If there isn't much time left you may just need to hold tight, or a volatile stock that bounces you need to again hold tight. If however it does go thru your long strike and you had put it on pretty far OTM the odds are it will continue to hurt. I've found I'm able to roll out to the next month when the stock is between my long and short strikes with a week or two to go for a small credit, however if the next month it continues in the "wrong" direction I generally close it. When its below your long and your completely ITM then that is the worst situation and you really won't be able to save it...again because you started OTM now you are SOL. There is no perfect and consistant solution because sometimes if you "adjust" it turns out you didn't need to or you decide not to roll and you suffer the consequences.
In order to answer properly your question, one must differentiate between two sort of adjustments. Strike adjustments and Expiration adjustments. But before that, the most important rule is: don't panic. If a position is taking away your sleep at night, you're probably trading too big. Keep your size so your losses are just numbers to you. Numbers are manageable, emotions are not. Also keep in mind that a strangle at 1 Sigma strkes away, has a probability of expiration outside the strikes of ~32%, but it has a probability of touch of 64%, so most of the time your strangle will be challenged on either side. So if you're playing this game, know what the rules are so you are not "surprised" when this happens. What works for me (most of the time) is: Strike Adjustments Only adjust your winning side Adjust this side to 20 - 25 Deltas (not more) Adjust against the market Adjust strikes only if it is early in the game Do not adjust often, let the markets run their course See intro - Be patient Expiration Adjustments Only adjust your losing side Adjust only to the next month Adjust to the same strikes for a credit or to further away strikes for a break-even. Never adjust for a loss. Adjust as late in the game as possible. If you're too far away, close for a loss and go to the next trade. Don't bother. Trade very small. Get experience. See what works for you. Some underlyings correct more often (don't touch those), others are more trendy (adjust those more often).