You guys have to get out of your systems the guilt & feel sorry stuff and the notion that your clients think like you do.
You are in business to make money and you do that by rendering needed services or being available to render services. Get over it. There is no need to grovel or slave for a dollar.
Just because there is a drought doesn't been you don't have operating costs to meet. The bills come in whether you work or not. Only thing to add when you are working is the labor and consumables like fuel. blades, belts etc.
No need to make amends next year for lack of cuts this year. Then your going to cut yourself short becasue it is a rainy year and your gonna do 2 or 23 more than you planned or the weather will extend the beginning or end of the season with the same results.
As long as they are paying and your delivering the best look possible That is as it should be. It is not a problem.
In pricing flat rate the only thing that could ever vary was the cut count. Your always going to deliver the mulch, annuals, shrub trimming and pruning, ferts, clean-ups etc with out variation.
I always priced my non-irrigated site contracts 2-4 cuts less the irrigated ones.
Another way to handle this is with good software and specify a minimum number of cuts and a price per cut when exceeding that. NEVER give anything back unless you get something in return. It is not your job to be a benovolent contractor.