It's a fair point. I've certainly seen the sales team promise something that, as an engineer, I have no idea how I'm going to implement. Some days I wish I could join the sales folks when they're giving their pitch just to make sure expectations are kept in line (from both sides).

That's why I always give a little leeway if I can. If they want their report changed from monthly to weekly, I'll do it. But sometimes it becomes clear they're just trying to take advantage of me and get extra work done for free. After all, why would they pay for a bar graph AND a pie chart, with both of them being shown as monthly and weekly reports, when they could just pay for one and then say "oh that's not what we meant, can you change that?"

I certainly will change that, no problem. But only if I have hours left after I complete everything listed in the original SOW.