Cadence is the frequency at which previous OKRs have to be graded & new ones created. All the material out there on OKRs talks about quarterly cadence. That is because for majority of the teams, quarter seems to be appropriate timebox for executing OKRs. Not too short to be inconsequential, not too long to make the OKRs irrelevant.
From our experience of building UpRaise, more often than not the quarterly cadence works well for team & individual OKRs. Because team & individual OKRs are tactical in nature. But when it comes to company level goals they are more strategic in nature & thus tend to have longer duration for execution. By no means this is a restriction & teams are free to choose their own specifics.
Primarily, OKR cadence will depend on following variables
Stage of the business
Nascent, startup, scaleup, established etc. For example, startup who is still searching for product market fit will tend to have high frequency (short duration) cycles whereas an established business where all processes are set up will be satisfied quarterly (or even longer) cycles.
Stage of the employee
If the employee is at a junior level & new to OKRs, the initial couple of cycles can be of shorter duration.
If the industry is prone to frequent disruption, definitely the businesses should have shorter execution cycles.
While it is possible to have different frequencies for different departments or different levels (team, individual) of OKRs we recommend staying away from such a set up at least in the initial stages of adoption. Different cycle duration can become obstacle in cross functional collaboration & add to the operational overhead.