Hey!
Of course! I would say that there are a couple of main reasons why preparation for a DTC AC can take longer than for a vac scheme AC.
The first is that DTC ACs often include a wider range of assessed tasks, as others have mentioned. This will vary between firms, but it is quite common to see additional written exercises, case studies, or multiple interviews. As the firm only has a few hours to assess candidates (as opposed to a week or two on a vacation scheme), they tend to test more competencies within that shorter timeframe. As a result, you often need to prepare for a broader range of assessments, which naturally takes more time.
The second reason is that the AC is usually your only opportunity to demonstrate your motivation for the firm. On a vacation scheme, the firm can observe how you work over several days, see how you interact with others, and hear your thoughts in more informal settings. For a DTC AC, they do not have that extended exposure to you, so it is particularly important to be able to articulate clearly why you want to train at that specific firm and what draws you to their work. I found that this required doing more in-depth research beforehand so that I could communicate my interest convincingly in interviews.
A related point is that, on a vacation scheme, you are often learning about the firm as you go and can tailor your understanding throughout the week (before the final TC interview). With a DTC AC, you generally need to have that level of understanding before you arrive, which can mean spending more time preparing in advance.
I hope that makes sense!