Run Transaction Log backups only during Work hours?
On a technical level: is this a good practice or not?


I would say not. If the database is experiencing no activity at all during the business off hours, then taking the backups is very low overhead. On the other hand, if the database is experiencing any activity during business off hours then not taking the backups is a serious problem.

My stance is that taking the backup has advantages:


is "future proof": if someone adds an off-hours job, your backups will 'just-work'
less complex, is easier to explain/understand/operate: no special hours for log backups. No special recovery procedure for 'off hours' vs. 'on hours'
it does no damage