I agree with most of this, but caution against bidding more hours than you think the project needs in order to raise your "effective" rate. In addition to being slightly skeezy and potentially queering expectations on future projects, doing this also has the practical risk of putting you on the hook for additional work if your client starts aggressively project managing you; after all, they bought the time.
Another way (also skeezy, I think) firms play this game is to double-book and have teams juggle multiple projects, thus genuinely spreading the hours on the project out while keeping effort constant.
I really think the thing to do is to be upfront; if your rates are raising, they're raising. If your customers want to mitigate that risk, they can pay for it: pre-buy time commitments at a discount from your current rate. I think advanced purchase is a more effective (and more professional) lever to use than rustproofed hourly quotes.
I should be clear-- I'm not saying you should make up fake hours or pad your estimates to conceal a higher rate-- you should work on the basis of flat fees. If the client thinks you're not worth the money, they can choose someone else to do the work. If the project takes longer than you expected, you lose, and the client wins. I think that's different than the "they bought the time" approach you were (sort of) attributing to me.
Another way (also skeezy, I think) firms play this game is to double-book and have teams juggle multiple projects, thus genuinely spreading the hours on the project out while keeping effort constant.
I really think the thing to do is to be upfront; if your rates are raising, they're raising. If your customers want to mitigate that risk, they can pay for it: pre-buy time commitments at a discount from your current rate. I think advanced purchase is a more effective (and more professional) lever to use than rustproofed hourly quotes.