Time in Orps is usually measured as it is in the real world: Seconds, Minutes, Hours, Days, Weeks, Months, Years, etc. In general however we want to focus on the time to complete a task and combat time. These two categories are the important ones for us.
Time to complete a task
So you need a character to pick a lock, fix a jammed firearm, or solve a complex math formula in their head? Then you are looking at Time to complete a task. Most things we care about in this category are measured in minutes and for simplicity five minute increments are encouraged. These are usually related to a target number and it is fairly easy to take the target number and simply convert it to minutes to set a basic time to complete a task. If it is a skill roll rather than a contest things are often a little harder to set specific times for, but the die roll in minutes is a good number to use in most cases.
A few tasks, such as building something or designing something, can take much longer than a few minutes. The idea may stay the same, but the time could be in hours, days, weeks, months, or even years. A good idea may be to simply roll a die and perform your skill roll or contest roll on a regular basis depending on the scale needed. Building a car form parts should take days or weeks. Fabricating a car from raw material could easily take a year and may best be measured in months.
ORPS uses 1 second intervals during combat. The main reason for this is because few people can perform multiple actions within 1 second. This streamlines combat in particular and if needed lets us take certain actions over multiple turns when needed without making everything happen at that speed. The downside is that this can mean sometimes a character spends a few combat turns in a row not really doing 'anything'. In these cases you may want to decide how long a certain action or set of actions may take and streamline game play during such turns.
To use a modern example of this, a group of PCs encounters a group of NPCs who attack them with rifles. The PCs dive for cover on their first turn, but can't see the enemy from behind their cover so they need to take a turn or two moving into a better position. In the meantime the enemy is firing rather randomly trying to flush the player group out of hiding. You don't need to roll each NPCs turn and decide who may be in the way of random fire and instead roll a generic contest of highest NPC attack versus highest PC dodge, letting the players know the results as they move into position. This all plays into knowing when to roll and when not to roll dice.
Certain actions can be 'combined' into a single turn, some of these even gets special names such as 'Charging the Enemy' or 'Moving and Firing'. Most of these will be covered in another section.