My LTD plan pays 60% but some policies do pay 70%, it all depends on the company you worked for before becoming disabled.

The 60% or 70% is not on top (in addition) of SSDI, we are only able to collect a combination of the two benefits, at least that's the case for me, the two work in conjunction with each other.
For example, my SSD doesn't equal 60% of my prior pay so the LTD carrier is responsible to make up the difference to bring me up to 60%.

In order to collect more than just what SSD pays, you would've had to be able to collect on either a group LTD plan offered through your employer, or purchased a LTD plan on your own. Private LTD is very expensive, but the good thing about having such a plan is that private LTD doesn't usually offset what SSD pays, thus leaving the disabled person in a position to not only collect their full SSD, but also to collect the full percentage of the disability plan that they purchased. Basically a person could collect on both and have a good stream of income while disabled.

I'm not on a gravy train by no means, I'm under group LTD, my SSD & LTD are both taxed leaving very little to live on verses what I was making in the past.