Ok but what if you buy an itm call on an option with a .7 delta and the underlying is rising? Is there not a good chance your call option will increase in value?
Assuming a lot of time hasn't passed, and volatility wasn't exorbitantly high when you purchased it and afterwards came in considerably, the answer to that is obviously yes. I don't understand the intent of the question.
The question would still be, were you better off just buying 70% of the underlying. Which would 100% definitely increase if the underlying was rising, regardless of time, speed, and any change in volatility.