This campaign will attempt to cut down the number of skill checks for routine tasks such as Perception to notice something obvious, or operate a device you have long-term familiarity with. Unless the character is in combat or different sort of stressful situation where timing or quality of execution is essential and carry negative consequences on a failure, and as long as does not suffers due to a negative DM modifier (such as due to multitasking, shortening time required, or a negative condition such as the effect of a wound), the player may not need to make a check to succeed if the character has a skill of 1 or higher and the GM considers that to be sufficient level. Typically skill of 1 or higher is enough for routine tasks (driving a vehicle in familiar environment), and skill of 3 or higher is enough to assure success of specialized routine tasks. (doing immediate repairs to a vehicle with enough parts and a manual).
Check with the GM if your skill value (minimum of 1) is enough to provide the bare minimum of success. If they agree, you succeed with an effect of +0. If the effect is important to the roll result, you must always roll as normal.
Perception checks that are unimportant and only serve to see who first notices something, are never rolled. The GM generally chooses a level of visibility (-1 is obvious, 0 is obvious but requires concentration to spot, 1 is somewhat hidden unless you know where to look, 2 is well-hidden, like a book of Where’s Waldo) and lets anyone or a random character who have INT DM of that value spot it first. If no player can match that value, the GM may increment the time needed to spot and apply +2 from Go Slower. If that would still not be possible to automatically perceive, the GM should call an INT check from each player.
A Perception check is an INT check to notice something peculiar or out of ordinary, with a follow up EDU check to properly identify what it is. The Recon (INT) skill is applied in tactical perception where immediate identification and classification of tactical information is applicable; a follow up EDU check is not needed if the identification falls in documented military or paramilitary classification. Otherwise, the EDU skill can be complimented with applicable skill.
Bonuses from Going Slower (Corebook, pg. 63) and Tasked Chains (Corebook, pg. 63) do not stack. This is because there is a finite amount of benefit you can have if you get help from someone else or a previous action, and taking precautions and double-checking before acting. You take the highest value among all DM bonuses between the two. Examples:
Other factors (assistive equipment, for example) stack cumulatively as normal. DM penalties from various factors (such as Go Faster and a failed Chained Task) also stack as normal.
If the situation allows, and the circumstances change significantly, the GM will allow you to retry a test that doesn’t carry negative consequences on a failure that make impossible to retry it in the same way. Usually, the GM will require a change or circumstance and the easiest way to change circumstances is to retry on another day for common tasks, or plan another laboratory experiment or streetwise investigation if this is something more involved.
When a Chained Task is retried, or if multiple different Tasks all serve as interchangeable Chain Link in a Chained Task, only the highest Effect among the checks provides a DM+X bonus to the follow up Chained Task.
You never ever should ask for advantage rolls. Advantage and Disadvantage checks are always due to uncertainty factors in a chaotic environment that you could not have anticipated. You can never ask for the GM to give you advantage, and must always be prepared for the worst. You can never ask for Go Slower or other compensating option after the GM announces a disadvantage to a check.
If the GM wants a random decision if an advantage or disadvantage must apply to a check in a chaotic situation with too many external factors, they roll 2d6 and apply disadvantage on values 2 and 3, and advantage on values 11 and 12 in chaotic situations; just values 2 and 12 is less chaotic.