I respectfully disagree. This is a relatively easy job with great rewards ( what happens if/you find rust in the window channel?). Yes, it gets easier the more you do it - and I have done about 5 now and am in the middle of doing a W116 windshield ( wrong gasket

). I have 9 cars and they all have rubber gaskets so farming this out time and time again is not cost effective for me.
I would rather do this and leave rebuilding my front end to someone younger and more supple, given the choice.
It certainly helps to mitigate your risk and have a plan B if you are going to do this.
Knowing months ago that I would be doing this, I found a decent windshield and rear window at a upullit for about $25 total (on sale). The glass I have is good anyway, so I have a backup. And right now there are 2 W116s in the same yard with good glass and trim, and one of these even has my color interior.
That's my story and I'm stickin to it( watch me screw up this weekend).
Rick