I think the slight shadow irregularity is because it isn't one continuous LED light strip. Not much you can do about it and definitely something that you are noticing because you just installed it! Once the backsplash is installed and you have stuff on the counters it will be a non-issue.

I agree with chispa that it'll be a non-issue once everything is in. The important thing is no shadow on the work surface IMO. I looked at my under cab lights which are a bit different than yours but are also LED strips - mine are in middle of the space so maybe that's why mine don't cast a shadow, If you're still tweaking things, I do highly recommend having them on a dimmer - that's a feature I find I use a lot!

I think it looks fine. One thing I typically do is make sure the light strips stop about an inch away from the ends of the cabinets to avoid the glare on the adjacent cabinets/walls. If it bothers you, you can always put electrical tape over the light strips on the ends.

Thanks for the advice about the ends. I was actually measuring things out to get the longest strip, but I see what you're saying about the sides. The cut marks on the strips are about 1-2/3" apart, so I could take a cut off each end if needed.

IMO the shadow looks pretty bad, and will continue to look bad with drywall, stone/tile or any decor placed there.

It appears you are not using ceiling lights for counter task lighting, as I don't see any ceiling lights in-line with the counter edge (I do realize you have any ceiling lights turned off for the pic). So that means you are forced to use the UCL for your principal task lighting,

Each channel varies by manufacturer on how much the sides of the extrusion blocks the light from the tape strip. In your case, I would manually rotate the channel to see if you can get the wall wash higher, and still provide some task lighting towards the center of the counter. If it works, you can DIY some blocks to mount the channel at an angle, or just buy angled channel.

What you have is on the left in this illustration, the right is a better placement (if you have proper ceiling lighting), but being at an angle (no illustration of that) might help. An extruded angle channel has a wider throw of light than the flat channels.

It is noticeable. I don't think the tile is going to change the shadow. Your issue isn't unlike the seam in the granite. We agonized over stuff and, in the long run, does it matter?

Who, besides you and family is going to l see it?

What backsplash have you chosen?

BTW, is it on a dimmer switch? That might help.

For 3onthetree, this is where the ceiling lights are amd how they light the area.

Those ceiling lights are on a dimmer and I think at full in that photo. They are about 16 inches out from the front of the top cabinets and about 5 inches out from the front of the countertop. Also note the ceiling has a soffit above it in this area for ductwork, so is only about 84 inches high, not 96.

Note the upper cabinets at question here are 29 inches above the counter, not 18. Whether I'll put a strip under the cabinet at the far left, I don't know. I don't think it is needed. This is a wet bar in a family room area, so would often be used with the ceiling lights dimmed or off, but only for a few minutes at a time, not a kitchen with hours of food prep.

I tried the lights pointing straight at the wall, and at 45 degrees, but those didn't light the front edge of the countertop as well as straight down. Some shallower angle, say 20 degrees from horizontal gets the whole wall and most of the countertop to the front edge lit. My issue isn't with the existence of the shadow on the wall, it is that it is wavy and not straight.

For judianna20, I don't have a backsplash, but was thinking something with a matte and not shiny finish.

Info that this isn’t a kitchen work space makes a huge difference, for me anyway, in my view of your wavy shadow issue as well as how much light is needed on counter surface. For me, it would make it more important to have the UCLs on a dimmer - that would be a very useful function in a wet bar in a room where TV watching or diffused lighting is wanted. I agree with your idea of a matte finish for backsplash - seems like it would bring less attention to a wavy shadow line. Maybe any pattern in the BS should be anything but horizontal - a vertical or random pattern - to prevent wondering if it’s the shadow or BS line that’s not perfectly straight.

ETA ; I meant ’ if it’s the light (not shadow) or BS that’s not perfectly straight’. You likely got what I meant