I would do these especially to control transaction log growth,

1. If possible split the query to iterate each table separately instead of running updates for all 50+ tables as a single batch.
2. Batching updates, preferably on clustered index using careful batching approach defined here only if applicable.
3. Increase frequency of log backups.

I would do these especially to control transaction log growth,

1. If possible split the query to iterate each table separately instead of running updates for all 50+ tables as a single batch.
2. Batching updates, preferably on PK clustered index using careful batching approach defined here only if applicable.
3. Increase frequency of log backups.