Traspararent evaluation in lab exams -- good or bad idea?
My experience (in the UK) is that provisional marks for all assessments, whether coursework or exams, need to be returned to students within a set timeframe. 15 working days is a common one, but this varies from university to university.

Early feedback is a good thing, as you said, as it lets students know where to concentrate their efforts. This may include subject areas, but also, sometimes a student receiving a lower mark than they hoped for, might be spurred to working harder towards the next element of assessment.

I say provisional marks as, although the marking standard will have been internally checked at this point, it unlikely to have gone to an external examiner to ensure that the standard is comparable with other universities. So, the mark could potentially still change after that process.

The question asked if there are any cons with this approach. I can't think of any, but I'm really not used to the idea of marks being held back unnecessarily.