ETL may be the best and only scenario but thinking of a particular table we have in our environment, I'm not sure that there would be any justification to disable and then rebuild the indexes. This particular table has nearly 9 million rows with 14 different indexes. This is a vendor app and they use hints all over their code so I can't disable (or remove) any of the indexes even though some of them appear to be redundant.

Side note: my boss asked me to see why the database seems to be growing more rapidly than it used to. When I looked, I found this table consumes the largest amount of space in the DB at 12+GB. Almost 8.5GB of that is indexes alone. I suggested we look at what indexes can be removed and changed and he said to leave them as they are since it would likely break the vendor app. Interestingly enough, we have another table with 23.5 million rows that only consumes 7GB of the DB.

In this case, it seems it would be better to leave them enabled during an ETL process so that they are maintained rather than having to wait an hour or two after the ETL for the index to rebuild. It seems that there must be some sort of tradeoff point where it is more efficient to leave the indexes enabled?