Does this constitute a gap? Venues are 5 minutes driving distance away, but we live in a major city so factor in maybe a 5 minute walk to your car as well (street parking is tough, and most will probably park in a garage close to ceremony...reception has many parking spaces).
4:00-4:30 - Ceremony
5:00 - Cocktail hour, with doors technically allowed to open at 4:45 but nothing served until 5:00.
So there's some awkward lag time, admittedly, if you leave the church right away and drive to the venue. Is this too much, or within realm of reason? I would think the latter, but I'm learning lots of stuff from The Knot and I want to make sure.