So, it was "re-used briquettes" and not re-used lump?
@Johnpv and
@1buckie have some excellent points and concerns.
I reuse both lump and briquettes. Leftover lump is not such a big deal.
However, leftover briquettes tend to lose some of their "heat" properties after one use.
I will shake them down to remove the ash. They go from marshmallow size, to "mini" marshmallow size. (slight exaggeration)
Then I will mix lump and used briqs and dump them un-lit into a charcoal basket. Then lit charcoal goes on top. (Minion method)
I like to go with fresh briqs or lump in a chimney to get a good heat "blast" to a cold kettle when starting a cook session, then adjust the vents from there.
BTW, this thread potentially belongs in the
Kettle Cooking Discussions section.