In the UK (and hopefully the rest of EASA-land) one can alternate between a revalidation by flight and a seminar (providing other criteria have been met; otherwise it's both). However, one has the choice of doing a flight test instead of a seminar. I've attended one seminar and whilst there was some value to it, for myself I find I get more value from a flight with a FIE. The latter is more expensive and is also more stressful, but I come away thinking that I've been given a positive attestation regarding some of my performance as an instructor and had some shortcomings highlighted. There is plenty of opportunity in between the briefings and the flight to discuss latest issues and direction that LAPL/PPL instruction is taking.
in the 2 day seminar I did attend, I suppose active participation accounted for an hour or so - the rest was more passive. Actually, the best bit was meeting some other instructors I hadn't seen for years and catching up; perhaps the best bit of any seminar.
I'm not sure really quite what the seminar is for, apart from an additional part of renewal for those who haven't met the revalidation criteria. There is a suspicion that some people might use it as an excuse not to fly with someone who might show up their deficiencies.
TOO