Three to five objectives per period is the common guideline, each with around three key results. Google's guide to OKRs recommends this range and warns that more objectives can over-extend teams and spread their effort too thin. Fewer goals force the conversation about what matters most this quarter. If every objective feels essential, rank them and move the lowest to a list for the next cycle. Teams new to OKRs often start with one or two objectives and add more once the weekly rhythm is in place. Source: Google re:Work, Guide: Set Goals with OKRs (2016).

For ambitious goals, an average score of 0.6 to 0.7 on a scale of 0 to 1.0 is the usual target. Google grades its OKRs on this scale and expects that average across all OKRs, treating a full 1.0 as extraordinary performance. A team that hits 1.0 on everything is probably setting goals too low. A low score is a prompt to look for blockers and reset the next quarter's ambition. Agree before the quarter which objectives are stretch goals and which must be fully met, so scores are read the right way. Source: Google re:Work, Guide: Set Goals with OKRs (2016).

An objective is what you want to achieve, and a key result is the measurable evidence that you achieved it. John Doerr describes an objective as what is to be achieved, no more and no less, and says good key results are specific, time-bound, aggressive yet realistic, and measurable and verifiable. He quotes Marissa Mayer: it is not a key result unless it has a number. A useful test is whether someone outside the team could look at the key result at the end of the quarter and say yes or no. Source: John Doerr, Measure What Matters (2018).

Google's guidance and many OKR practitioners keep them separate from individual performance reviews and pay. Google's guide states that OKRs are not synonymous with performance evaluation and are not a comprehensive way to assess an individual. When pay depends on hitting a key result, people tend to set safer goals, which defeats the purpose of stretch targets. Use OKRs to focus the team and surface problems early. Judge individual performance on skills, responsibilities and contribution, with OKR results as one input to the conversation. Source: Google re:Work, Guide: Set Goals with OKRs (2016).

Check progress weekly, and grade the OKRs formally at the end of the quarter. Christina Wodtke recommends a Monday meeting where the team reviews each key result, rates its confidence of reaching it on a scale of 1 to 10, and commits to the week's priorities. A confidence score that drops two weeks in a row is an early warning worth discussing. She pairs this with a Friday session where teams share what they finished, which keeps morale up while goals are ambitious. Keep the check-in short and focused on what changed. Source: Christina Wodtke, Radical Focus (2016).