For me, it really depends. For my Greek ABD, the hotels were relatively reasonable (I don't remember the exact amount), so I booked through ABD. But for my Scotland ABD, it's like $700 per night. I just can't justify that! So I'll be booking Scotland on my own. For Southwest Splendors, pre-nights weren't offered, so it wasn't an issue (I stayed just outside of Phoenix, then went back to the airport to turn in my rental car & join the group transfer). For Knights & Lights, I was staying in Winchester for the first couple of nights, then taking the train into London for 3 days, so the transfers were kind of a moot point, so I booked on my own. (I just took a taxi from the hotel I was staying at to the hotel where the ABD started). And pre-nights on the Med cruise add-on were through
DCL, not ABD, and transfers were extra. So I booked on my own. For Alaska, the pre-nights were fairly reasonable, plus I couldn't get a room myself at the same hotel (it was sold out) and I was arriving after midnight, so I decided to book with ABD.
I think you really have to judge on a case-by-case basis. Booking pre- or post-nights through ABD is definitely easier, but sometimes it's just not practical.
Sayhello