It can be done and was done by my GM on a few occasions back when we played in the 80's but we used the original rules back then. Specifically it was used when one character got separated from the group and he ran individual one on one until that character got back to the group.
And have run into that situation with other games too - was in an AD&D campaign where we took on the wrong monster and only one guy survived. Was run as an individual survivor campaign until he got back to a town and then we started the group again with new rolled up characters that he "recruited".
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