Storage requirements & incremental backups

The problem
Making regular 'full-backups' every other week incurs a high toll on uptime and resources. Each full backup needs 65% free disk space, and enables maintenance mode for a significant amount of time. This is theoretically unnecessary because most of that data is already stored off-site in the previous full-backup. The whole process is for the most part redundant.

However, regular full backups are currently necessary because the backup app implements differential rather than incremental backups.

A differential backup always take the last full-backup as starting point, making every partial backup larger than the previous one. An incremental backup doesn't exhibit that problem because it takes the last full OR partial as starting point.

The solution
By implementing incremental backups, the need for full-backups reduces significantly. The only remaining reason to create full-backups is to cut back on restore times. I feel like a lot of admins would take the trade-off of increasing disaster-recovery times in favour of uptime. Choosing for example to make a full-backup once every few months.

Also, if a regular full backup isn't necessary, an admin could choose to incur the major time penalty of writing a full-backup directly to off-site storage. This would reduce the disk space requirements of the nextcloud instance by ~65% (!).

What are your thoughts on this? Would you consider implementing incremental backups?

EDIT: Readability.

Start by reviewing the backup app’s current differential-backup implementation and its backup and restore flow; the issue names no files or tests. Clarify storage, scheduling, restore, and maintenance-mode requirements before implementation. Done would require an agreed incremental-backup design and validation of disk-space and restore-time trade-offs.