overhead of varchar(max) columns with small data

Question

As part of a bulk load of data from an external source the stageing table is defined with varchar(max) columns. The idea being that each column will be able to hold whateve

Answer 1

As far as I know, the overhead that you are probably thinking about (storing the data out-of-row in the same way a TEXT or BINARY value is stored in sql server) only applies if the data size exceeds 8000 bytes. So there shouldn't be a problem using this with smaller columns for ETL processes.