Depends on the coach and the pretty adequate racer. There are some that believe that you don't need any more leg strength than your granny to ride a bike and by implication that muscle hypertrophy does not occur during training, and there is no need to train your upper body or do any off the bike training.
All this is in direct contrast to what the offiicial british cycling website says and the top riders do. Anything the top riders say they do is supposed to be to mislead their rivals so that they train incorrectly.
You really couldn't make it up. For them it's all about aerobic fitness don't you know.
IOW there's good and not so good advice on all forums. Certainly Bike Radar has more contributors to the training section but IMO it's no better than here for advice. This forum is much more healthy as any debate is not subject to heavyhanded moderating and influenced by pathetic posters (big girl blouses) who whine to admin when they don't get their own way. Nah this forum is much better.
Back to the OP. Time Trialling is about maintaining a high cruising speed between 90-95% MHR. This is hard to do as to do this you need to have the ability to suffer. You can train yourself to do this.
Road racing need more bottle and bike handling skills.Which one you choose depends on your physical and psychological make up. Try both as the training for both is the same although you will need to ride with groups to learn how to follow a wheel.