My new (Aomei) incremental backup policy (need advice)

Assuming AOMEI works like the other incrementals, you really, really want to roll that up into a new Full image at some point.

To recover with a Full + Incremental series of files, you need ALL the intervening incremental images.

I use Macrium Reflect. The Incrementals are rolled into a new Full image every 2 weeks.
Read here for my particular process: http://www.tomshardware.com/forum/id-3383768/backup-situation-home.html

At the next Full image, that should not contain anything you've deleted previously.
I know mine just don't 'grow and grow forever'.

It would be useful if you would provide the following info...

1. Your primary HDD is your boot drive which we can assume contains the OS (which is?) as well as other data, e.g., programs, personal data, etc.
A. What's the size (disk-space capacity) of that HDD? And its total data?
B. Can we assume it's single-partitioned containing all the data on the disk? Or is it multi-partitioned, and if so, can you provide a description of the partitions and the contained data in each?

2. You also indicate a second HDD presumably internally-connected in the PC (desktop?). Could you provide info re that drive along the lines in 1. above?

3. And you're using a USB external HDD for backup purposes. What's its size?

Depending upon the info you provide perhaps there are other backup options to consider.

Depending upon your response to my query I contemplated a possible optional backup strategy for your consideration.

However, it appears your present backup strategy amply fulfills your needs so I'm hesitant to suggest another option under the present circumstances.

Be that as it may...just let me make a few comments based upon my own personal orientation when it comes to this subject of backing up one's PC system(s).

First of all it's absolutely crucial for users to COMPREHENSIVELY back up their systems on a fairly frequent basis so as to maintain reasonably up-to-date comprehensive backups of their systems that they can use to easily and reasonably quickly return their systems (data) to a functional state in the event that disaster strikes in the form of a defective/failing drive or a hopelessly corrupted system caused by malware or misconfigurations of one kind or another.

In terms of carrying out these backups I am a strong believer in cloning the contents of one's drive(s) to another drive or drives. As a general proposition I am not a fan of either incremental/differential cloning or disk-imaging. Admittedly (in my opinion) there are situations where the latter form of backup strategy is useful when the PC user is particularly (or exclusively) interested in maintaining "generational" copies of their systems/data.

But as far as I'm concerned nothing really takes the place of having at hand what amounts to a bit-for-bit hard copy of one's drive(s) - where all the data is instantly accessible without the need for "recovery" processes. And that can be achieved through disk (or partition) cloning operations.

We use the Casper disk-cloning program to perform comprehensive backups of our systems. (Casper also has disk-imaging capability but as indicated above we rarely utilize that process). We have never found a disk-cloning program the equal of Casper in terms of ease of use, general effectiveness, and perhaps most of all - speed of carrying out disk-cloning operations when the program is utilized routinely & frequently. However, Casper is a commercial program costing $49.99 so most PC users are loathe to purchase a program that they can obtain freely on the net. (BTW, I have no basic problem with the AOMEI Backupper program; it's a decent program based upon my limited use of its disk-cloning functions.)

In your situation your 1 TB boot drive contains about 200 GB of data while your 2 TB secondary HDD contains
about 700 GB of data. So the TOTAL data involved in your system is not more than 1 TB. Is that no so?

Might you consider multi-partitioning the 2 TB secondary HDD so as to create one partition of about 250 GB - 300 GB & a second partiton encompassing the remainder of the drive to contain the present data contents residing on that drive? So from time-to-time you would clone the contents of your 1 TB boot drive to one of the two partitions on the 2 TB HDD. Thus the 2 TB HDD would serve as a comprehensive (internally-connected) backup drive for your entire system. And that 2 TB HDD would be bootable as well.

Now for additional backup security (due to the value of your data) you've indicated you use (or plan to use) a USB external HDD. A wise decision to be sure. If that USBEHD had a disk-space capacity of 2 TB (or greater) you could utilize that drive as the destination drive for the cloned contents of the 2 TB internally-connected HDD so that you would have an additional comprehensive backup of your ENTIRE system. (And depending upon the disk-cloning program & your system BIOS it's even conceivable the cloned USBEHD would be a bootable device while so connected!)

I don't know if the above holds any appeal for you. Probably not I would guess since I believe you're quite comfortable with your present backup strategy. But I thought it might be of some interest to you.

BTW, because of its inherent speed, we frequently use Casper to clone our systems on a daily basis or a few time per week. We sometimes also utilize its scheduled automatic backup facility - many disk-cloning programs also contain that capability. Casper does have a 30-day Trial Version that you might want to try out (although it has some limitations particularly with respect to partition cloning). See https://www.fssdev.com/products/casper/trial/
If you do give it a "go" remember that its disk-cloning speed is reflected only when the program is run on a frequent basis. If your interest is only centered around backing up this or that system on an infrequent basis - say not more than once a month, then probably any disk-cloning program will fill the bill.