Since I started working as a “consultant”, I started using the exact same Evildoer tricks ! I’ve said “No” to partners coming with easy & urgent requests, just because I wasn’t feeling like dropping my work and doing these. To the juniors’ disbelief, I _gained_ their respect. This is also how I never got caught with the “can you stay all night/all weekend and try to get this done before monday ? Our boss just asked f…
I imagine this works as long as you can say no, requiring good financial management and marketing skills. Easy to say no when you are turning away work.
If your work is perceived as "hard" and you let your client do the "easy" part, then you can increase your fees (bigger impact, and more ownership for them). If your fees are higher than normal, then your client doesn't want to bother you with the "easy" stuff. You get hired to do the "hard" things. Doing "hard" things often involve saying no to spurious/out of scope requests. Etc etc...