One of the things to bear in mind with this theory study is that it never was intended to be an "academic" test. The government of the day does not want the ability of someone driving on a public road to be determined by their IQ. It is tempting to say it is pretty straightforward and you tend to find it easier if you prepare well for it. I hesitate because not only was the national theory pass rate declining pre-pandemic but also "effort levels" are extremely subjective. What one person might consider practising hard, another person would consider hardly making a serious attempt. For a general figure though, if you were able to apply what I would call focussed practice for 1 hour a day, and you kept that up for 2 weeks, I wouldn't mind betting you will be there or thereabouts. Try to think beyond the regurgitation of factual information though, the idea behind the theoretical knowledge is to be able to retrieve, recall and apply it when you are actually driving. If you simply remember it in your short-term memory for the purposes of a one-off theory test, you are unlikely to be able to make practical use of it.