I'm my experience, I found its customary to give at least two weeks notice when separating from your employer. How does this work when you're in a position with access to all systems?
There have been two other individuals in my time at my current employer that quit on the spot. When I enquired about this, a coworker informed me that this is normal because of the access those individuals had.
I would like to leave on good terms and I'm not sure what the etiquette is in these situations.
( 6 months ago )
It is very unlikely that those individuals gave zero notice. What almost certainly happened is that they gave the expected amount of notice, but the company decided not to require them to work that notice. That option is always open to a company, and is frequently used when the employee has access to confidential information. Typically the person still technically works for the company through the notice period, and is paid, but they don't have to show up for work and their access privileges are revoked. Alternatively the company may have agreed with the employee to waive the notice period, so the employee could start work at the new company immediately.
in the first case it's the company's decision, not your colleagues. In the second both parties have to agree. If you are in this position, you should give the normal period of notice and wait to see if the company wants to take either of those options.