Upload & Sell: On
I figure the "pro" would come down on me for suggesting a superzoom lens over a L prime like the 35L, 50L, etc. But not everyone has that kind of budget to spend for the primes unless they make money from photography. Life is about compromise. All of my primes are non-L. I rather have three non-L prime than one L prime.
No, a real pro will always consider the benefits of weight and simplicity, vs. too many pieces of unused gear to keep track of and haul around all day. Many a time I've rued the fact of bringing and extra body, lenses, and large camera bag full of other goodies, as opposed to the one full frame body + super zoom I actually used all day and into the night. I've learned a bit since then! If I know the parameters of the activity, I prefer the freedom of one body/lens around my neck and anything else deposited somewhere else. I tend to wedge into odd nooks and crannies for support and also unusual vantage points, and bulky extra gear can actually be a danger for a klutz like me.
A good example was one of my favorite-ever assignments: two days to cover the Space Shuttle move along the streets of L.A. The first night was handled by the 16-35L II zoom, plus 50/1.2L, from pre-sunset to about 11:00 PM. This was very localized at a 405 freeway overpass, covering about three blocks of distance, back and forth and milling around. The next day was a multi-mile trudge in hot weather (yes, with back-up body and "light" camera bag), following the Shuttle from its overnight spot at the Forum, with descent on Crenshaw Blvd. I ended my day with Debbie Allen dancers (and other speakers, etc.) performing at the Baldwin Center mall -- perfect lens for that, wide open in bright shade. That day was covered completely by the 28-300L, using its full range of focal lengths, and really no others were needed, for some of the best coverage I've ever produced. That wouldn't have been the lens for a night shoot, but as a f/5.6 to f/8 daytime lens, amazing results!
Just for comparison: an equivalent selection that would improve speed and performance to a noticeable degree would be the original 24-70/2.8L, 70-200/2.8L IS and 1.4X II converter weighing 2640 grams, or 5.8 lb., compared to the 28-300/3.5-5.6L IS at 1670 g, or 3.7 lb. That's a considerable difference in weight, and expense.