Yups, journalists, street photographers...

I do my best with whatever there is to photograph, and I'm getting better at it. I'm just wondering. Looking around and thinking if maybe I'm doing something wrong again. Like the format. I'm almost convinced to MF and LF after this talk here (if I had more cash...) Or Ektar vs. Velvia for landscape - still no clues here, I guess I'll buy both when I'll go through this few rolls I have already.

To you give an example of what I'm worried with: what led me to selling almost all I've got, buying best gear I could, and in consequence to writing this rather long question, was a photo I wanted to print as 40x60cm (still no clues if you've been writing about 40x60 cm or inches, but it's a nice coincidence) for an exhibition I'll have next month. As far, as I can recall, I've took it with T50 lens "aus Jena", which is DDR version of Tessar, and my old trusty Praktica it came with. I don't know if someone did something wrong, like putting one lens back to front some time ago, or it was me being stupid while taking photo or scanning, the image had no sharpness. It was OK on 10x15cm print, but looked almost like a pinhole image after scanning, just as if I'd scan the 10x15 print itself. The solution was simply to choose and scan one more photo - this time on a "real" scanner.

The problem was not a gear failure, which happens, but it was in my workflow - that is the fact I was relying on poor quality 10x15 prints to judge my work. I should be aware of the failure earlier, or take care while taking photos. It shouldn't go this way. No clues how many photos I've wasted. And since then, I'm really worried and taking care, reviewing and reevaluating all I've done so far.
What I'm afraid of is also a situation when I'd hear "no, no, sir, we don't need your photos, we're looking something better. (You should have known X, Y or Z while making those.)". Good if I'd hear "Get back with A, B or C, then we'll talk" afterwards. Hence the question about reasonable limits of what I have and can work with.

I know this is photographers place, not photo agents, maybe that's why there are no definite (yet still personal) answers.