Hotel blocks. When are they necessary?

I think it's worth it to at least setup a courtesy block - this guarantees room availability for those who choose to book a room, it costs you nothing to setup (and there's no obligation for you to pay for unused rooms), and often times, hotels will give a discounted rate to guests staying in the room block.

I would just do a courtesy block as well. It just gives a discounted rate, and any unbooked rooms after a certain date are released. You're under no financial obligation.

I agree with the previous posters - no harm in asking a hotel for a courtesy room block! Ours is throwing in extras like shuttle service to our venue and a free night for us (even though we live 40 minutes from our venue, it'll be fun to have a night away from home!) if a certain number of rooms are booked.

Our reception venue did give us the information for a nearby hotel that offers a free shuttle service for guests, which I thought was awesome. I just wasn’t really sure about the whole financial aspect of it. Thanks, ladies!

Check with the hotel to make sure they can do a courtesy block, as not all hotels will do that. I live (and we got married in) a very touristy area. The vast majority of hotels here will require you to book a certain number of rooms and you ARE financially responsible for them even if not a single room is used. They want to guarantee payment for the rooms, so you're on the hook for it. But there's definitely no harm in asking if a courtesy block is available.

I would do a curtsey block and offer them the discount that comes with the block

Make sure you get a courtesy block so you aren’t on the hook for unused rooms.

The only time you really need them is if you are in tourist season and/or there are limited accommodations. A block does not always guarantee a lower rate.