Former Barcelona academy coach Jordi Condom Aulí on the Inside The Academy Podcast:

Rondos can be something cultural because, for many years, they have been part of the training at Barcelona. We started our sessions with rondos, and it was something cultural. Other countries and cultures have adapted this over the years.

Rondos can also start team-building because they are related to many different situations. You can adapt rondos to technical or tactical skills; you have everything in them. You can use them as a little bit of fun to start and break the first moments of training, and you can put in rules. We can do many different things.

The only thing rondos do not have is deep movement. You cannot synchronise a pass with a deep run in the usual rondo. You can modify it—for example, after six passes, maybe play a deep pass for a cross—but we use rondos more to start training, have a little fun and warm up. You can adapt them to many things, but they are more for starting than for working on one specific technical or tactical aspect.

[…] Normally, the players, or the majority of the players, have the ball in front of them. You can add a player in the middle in a ball position who needs to scan and check, but it is difficult to see a progression with a synchronised pass and a deep run by one player, because in a rondo you can always see the ball in front of you.

This is the only thing, but you can adapt other sizes. Even so, I sometimes prefer rondos to a passing drill because a rondo is about making decisions. You need to use oriented controls, think and see where the opponent is. The one, two or three players in the middle are trying to recover the ball, so it involves decision-making as well.

It improves fast touches and oriented control, as well as skills such as improving your first touch. After a few months or a year, when you start in a team as a coach, you can see the progression of the players in these short spaces and in their technical improvements.

A passing drill is normally predefined, a rondo is requires the player to choose and improvise. That is why I prefer it. It is more fun.