If you're going for a new job, you're increasingly likely to face an all day testing session like this. A staggering 34% of companies now use them for selecting graduate trainees and senior recruits.

The short answer is you can’t possibly have a game plan for every eventuality that may occur in these highly interactive 24 hours.

OK, that's not particularly helpful advice given so many companies are using them, but there are a few general rules that will at least mean you don’t get blown to bits by the first grenade lobbed your way.

DO be yourself

It’s the only way to get through a day long exercise. If you try and create a persona to suit the particular company, the likelihood is the mask will slip somewhere along the line. Maintaining a pretence is also a huge effort and you’re better spending energy on the tasks.

DO prepare

Knowing about all the different elements of the assessment up front will help massively when you are put through your paces.

Expect an ‘in tray’ where you have to prioritise a list of tasks and suggest a solution for the most important, and a group exercise along the lines of building boxes or bridges out of components where you incurr penalties if you beak the rules. You may face a presentation too, so check out our tips for this here.

DO contribute

It’s no use sitting silently hoping someone will pick up on your innate abilities. As one assessor says “we can only work with what we hear and see, we're not mind readers.”

DON'T hammer the free bar

It’s very tempting to grab everything going, but don’t take full advantage of the free facilities.

While it's unusual for assessors to mark your performance out of ten at any social dinner or get together the night before, getting drunk or committing social howlers while under the influence will not go unnoticed either. Enjoy, but in moderation.

DON'T monopolise

Going on and on about your own ideas while ignoring or trashing other group members is not a good way to stand out.

One candidate who performed well at a one to one interview came over as ‘aggressive and obnoxious’ in the team exercise, reports one recruiter. It’s as much about listening and bringing out the best ideas, promoting the best actions for the group.

But it could be worse...

Commercial or industry assessment centres are a picnic compared with what military types have to go through.

First off is the bleeper test where you run back and forth between two white lines in time to a bleep that gradually speeds until, ideally, you're a blur.

The interview is more like an interrogation where candidates are quizzed on their part of a planned group mission. It’s designed to test performance under stress – and they put the ratchets on.

“Some do faint during this exercise – but then we like to see how people cope under pressure”, points out one lieutenant.