I like looking at the <title> element from LTR/RTL (Left to Right/Right to Left) perspective.
It depends. For the most part, I'm going to try to have two keyword references in the title, sometimes three depending on the structural length of the title. I no longer stick to that 60-80 character limit although I always make sure the primaries are at the beginning. There are some instances where longer titles are required and they perform just fine. The goal is to make sure the words are organized in a way where you achieve the maximum visibility for multiple combinations moving Left to Right and Right to Left. Kind of like a scanning device. ;)
<title>Grand Widgets - Widget Solutions - Company Name</title>
The above doesn't work for me from a Left to Right perspective. You have two keywords back to back. Even though there is a separator ( - ), I believe you need at least one word between the two references for those to perform.
Now, let's reverse that and go Right to Left. Not a real good mix going backwards huh? You'll want to take that into consideration when using two instances of a keyword in the title. As you move forward in the title, how many phrases can be achieved? Then, as you move backward, how many more phrases can be achieved? Left to Right/Right to Left. Without "back to back" keyword references. I always get at least one word between and a separator ( - ) in many instances.
<title>Grand Widgets - Grand Widget Solutions - Company Name</title>
From my experience, having the second word, the space, the hyphen, the space, and then the repeat of the primary is not a problem. If it reads naturally, you can achieve great success using the above methodology. A search for Grand Widgets is going to light up four words in the above title, all at the beginning too. That's close to nirvana for me. I have implementations of five word titles where three word searches light up all five words. Add to that a well written meta description and you have a killer SERP recipe.
<title>[b]Grand Widgets[/b] - [b]Grand Widget[/b] Solutions - Company Name</title>
Note: You'll want to focus on using singular, plural, and synonymous keywords within title elements.
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