This discussion of the number of places which are allocated post results day is quite interesting. I am trying to understand what the stats mean.
For 2018, the figures for medicine and dentistry were:
Applications - 90,980 (presumably that is around 23,000 applicants, most of whom applied for four places)
Allocated places on A level results day = 8,650 (presumably the number of people who achieved the offer they had).
Following Monday = 9,300, so a further 650 applicants got places within a couple of working days of results day. Presumably, on a practical level, these must be people who were either allowed in with some slipped grades or from waiting lists as there was no time for interviewing new applicants in that period.
23/8 (7 days after A level results) = 9,620, so an additional 320 - difficult to guess what their route to an offer was
13/9 (28 days after A level results) = 9,950, so a further 330 places, which look like they may be proper clearing places.
So by far the majority of "clearing" places are allocated within a few days of results day, presumably to candidates who had already been considered by the med schools.
It would be very interesting to see a list of which med schools do what. I think Sheffield, Leeds and Exeter operate a waiting list and Newcastle will not re-consider candidates they have rejected. Reserve lists are great second chance opportunity, so the policies are probably worth considering when deciding where to apply. For Leeds, you need to be in the top third of interviewees to get an offer, but to get on the waiting list you can probably be significantly further down the ranking as they can only consider applicants with no other offers.
Apologies to those of you with offers 
for whom this is a rambling irrelevance 
......