Some people are able to stick to strict schedules and practice diligently at the same time every day for the same amount of time. Some people prefer to carve out time where they can, practicing at different times of day for different amounts of time.
Either approach is valid, but both have some inherent risks.
If you practice regularly, for the same amount of time, how often do you push yourself to do just a little bit more? And are you really engaged for the time you’ve set aside?
If you practice irregularly, are you practicing enough to make the progress you want to make? Do you find yourself going days or weeks without practicing because of a lack of motivation or discipline?
You might feel comfortable as a scheduled or unscheduled person, but your musicianship might depend on actively becoming the opposite.