I was thinking of this and thought I may link them to work anniversaries, for example 1 year, 5 years etc so had informally been thinking of them as anniversary surveys. We already do new starter surveys (after 3 month probation) and exit interviews so don’t want to go overboard but for us, finding out how people feel after 12 months would be useful as we seem to have a mix of those that stay for years and those that stay for up to 2 years.