OK. I arrived in kingman about 10 minutes ago. I left Mesa at 12:20pm, arrived about 4:20, rounded off. Four hours driving, and I'm in kingman, not across the Nevada border where she would have been when she began making calls.
I'm thinking she went on 60 (had to have), so at least one hour on that to get to 17 north. I kept going on 60, but figured out fairly quickly that she wouldn't have. 45 mph, traffic lights every other block, extremely congested, and she would have known that because 60 goes through PPL meeting burbs of Phoenix.
She had a choice of going up 17 all the way to I-40, then going east towards Las Vegas, or of going up 17 to bypass local traffic then cutting over to 60 on an east-west route that would have been 36 miles.
Going over to 60 would have put her on a fairly isolated road, especially that time of night, which may or may not have been an advantage. She could speed like crazy, but she also would have been more obvious because of the very light to no traffic.
Going 17 to 40 would have kept her most annoymous, part of a driving herd, and it's a fast route anyway, especially on 40 (75 mph).
I used to think she went 60 and then 93 so she could toss the gun and knife in the desert, but very much doubt now that she took that chance. There aren't very many side roads she could have taken along the way, and the few she would have had to go on to feel confident they wouldn't be found are roads she wouldn't have dared to go on in a economy rental car (low clearance) after dark, IMO.
I think she still had all the incriminating evidence on her when she made those first calls, and given the time frame, she must have driven very fast the whole way, not stopped to dispose of anything, and made calls at the very first opportunity. It's possible, imo, but not if anything went wrong, like an accident on 17 or 40 and a long back traffic backup.