No-one can tell you that as that depends on what sort of trader you are. How long you normally hold things for, what type of shares you have bought, what your stop losses are, if you set targets what they are..etc Having said that most spread bet trades are generally held for shorter times than standard share trades.
The times that spread bets are typically open for range from a minute by minute basis to a quarterly basis. For myself, days/weeks/months are the main timeframes I usually go for. Most trade via spreadbets at present. I will sometimes day trade specific news-related opportunities, but not often. Most of my bets are far-quarter ones (i.e. mostly March at present having opened before mid-Dec. Newer ones opened after mid-quarter will likely be June ones) even if closing them in days/weeks.