Unless you want dark spots, I would put under cabinet lights everywhere. If you have framed cabinets, there are some very thin LED lights that will allow you to run in a continuous line without cutting into the bottom frame.

I've never had a client complain that their undercab lights were too bright - go 400 to 500 or higher, but look for a dimmable system so you can turn them down for a dinner party. And be careful with the brand you select. If you go with the cheap ones from Amazon, they produce a green tint to the light. A better brad like WAC has a much whiter light, a better cri, and a lower failure rate. Tresco is another brand - they offer the widest variety in selection, color, lumens, and mounting options. As you plan the system, make sure you can get to everything and replace components if needed. The transformers are the first thing to go, but the leds do have a failure rate as well.

Towards the front is the correct location. If you are getting a line on the counter, then your receased lighting is not placed correctly. It needs to wash light down the front of the uppers and hit the front edge of your counters.

Our drywall starts tomorrow, and our electricians just did the hardwire in 2 locations specified by the cabinet maker. The cabinet guys will fish the rest of the wires for UCL under an upper cabinet and shelf, and inside 1 cabinet. I verified with him, are they really sure that this does not need to be done before drywall, and he assured me that this is how they do it all the time. I asked my cabinet maker to put a flush channel and LEDs right into the bottom of the cabinet, so really all I will see is a strip of light, nothing sticking out. I hope yours works out and you get those lights!