Worst part was I was at the end of the build and it was late, I was tired and achy but determined they would get finished that evening. But for the bottom two drawers I needed to be on the floor to install the slides as I hadn't really thought that far ahead when assembling them and may well not have decided on the drawer sizes. But for anyone that's had one knee replaced can attest, they ain't standard issue and it was uncomfortable to say the least which was another compelling reason to get it finished. So with both knees having been replaced it was a bit more uncomfortable.
One bad evening versus two just made more sense to me. Just needed to ice down afterward. Lesson learned, install the slides when the cabinet is able to be raised. I used a set of cut blocks made from scrap boards for the height of the slide so I could simply rest the block on the base and use a spring clamp to hold in place. Install 2-3 screws and move the block to the opposite side and install a few screws. So as all the drawers were at the same height I just had a set of 4 blocks cut to the appropriate height to use as guides assuring all were the same.
The hard part with 28" deep drawers and an assembled cabinet as this was, I had to lay down to get the back screws. Like working on a kitchen sink faucet under the cabinet. Royal pia for us older folk.
Yeah, A real pain those bottom drawers. I made a template for holding the slides in place while I drilled and screwed. Started out at the top with the template for the top drawer slides. It was, iirc, about 26" tall. Once the top set was in I cut down the template bottom by the height for the 2nd row of drawers, installed those slides and the repeated the process for the 3rd and subsequent rows. I still had to climb in for the last row. My cordless drill and driver having lights on them made a huge difference.
To add to all the work, my bottom drawers came out about 1/16" narrow and the cheap crap Rockler slides I used weren't having any of that. I wound up having to shim them. To top it off, the bearing retainer on one of them snagged on the slider as I did the first fit test. Imagine my dismay hearing the tick, tick, tick of ball bearings falling out. At 11:30 PM, that's about the last thing I wanted to hear. Found all but one bearing, repacked them and crimped the retainer. Spent waaaay too much time groveling and cursing on that cold and dirty concrete floor. I guess too narrow was a blessing - too wide would have been worse. And, yes, the next morning I was definitely feeling it. Thank god for Ibuprofen.
But, it's easy to forget the aches, pains and f*^%ups once it's all done.