How much time do you spend warming up for your workout? How much time do you spend on stretching and mobility? Personally, I bet I spend 5 minutes or less on this kind of stuff most days.

Who really wants to spend a significant amount of their workout time preparing to work out?

I say just get on with it.

Of course, there are times when it is appropriate to prepare to work out by spending more time on warming up, stretching and mobility. But if on most days you need 10 minutes to do a general warm up and follow that up with another 10 minutes of soft tissue work or mobility work, I think you are probably wasting your time. Actually, I tend to believe that if you cannot have yourself ready to go in around 5 minutes, you may want to evaluate some things in your life, one of them being your training program.

This isn't to say that I am recommending that you jump into your workout completely cold either. For me, the absolute best way to warm up and prepare my body for a lifting session is to simply start doing the main movement of the session right away.

As an example, this is a typical protocol* I would follow for a squat-heavy workout...

(A couple sets of) sitting in a very deep squat for 30-ish seconds, leaning and bouncing around to produce more stretch in different areas.
(A couple sets of) 5-10 bodyweight squats
(A set of) sitting in a very deep squat for 30-ish seconds, leaning and bouncing around, this time with an empty bar.
(A set or two of) 5-10 squats with the empty bar.

*I would likely do some ab work or different light intensity exercises amongst all of this.

Then I would begin to work up to the weight I plan to use for my first working set. Do a set, add some weight, do a set, and continue this until I reach the weight for working set #1. "Working up" is something you should always do anyway. It allows you to practice and groove into the movement you are training while using very sub-maximal loads. By the time you get up to your working weight, you will be plenty warmed up and acclimated to safely handle heavier loads.

My overall recommendation is to get on with doing the movement(s) that are on the menu for the session right off the bat. Don't waste so much time doing pointless things you read you should be doing in a magazine.