Hit or miss means that something was not carefully planned; aimlessly; without plan or direction.
An unpredictable event that produces results that may/may not fail.
At random; unpredictable.
1. We decided to buy a cheaper tv and the picture is a hit or miss.
2. Getting a good table at the restaurant is a hit or miss because of the no reservation policy.
3. The weather is so unpredictable in Canada, it’s a hit or miss.
4. I just started painting and it’s a hit or miss when I mix the colors together.
accidental, aimless, careless, casual, chance, directionless, incidental, irregular, random, spontaneous, trial and error, unplanned, unpremeditated