Yes, that is what I've seen. But it seems to be a poor way to diversify bond purchases across time. Example: suppose the yield curve is entirely flat, do you really want to time all your bond purchases to that yield curve? I've never seen this discussed pro/con.
If one sets up a ladder all at once, one is doing this in only one interest rate environment i.e. one snapshot of the current yield curve. I would think the purest way to set up a bond ladder is to buy the longest out maturity on the ladder and perhaps a few other points. But don't buy it all at once. This would take some patience and follow through.
I've never owned a bond ladder.
A few points:
1. The key point is that you really don't know where interest rates are headed for the long maturities. Sure, we can all see that in a few weeks, short term rates will very likely be raised another 0.25%. What happens to the 5-year, 10-year, and 30-year rates, it's anyone's guess. In general, over the past couple weeks, 5-year and longer term rates have fallen slightly. With laddering, you're taking the "timing" aspect out of it. You have a bond/CD maturing, you just roll it out to the far end, without any real fussing about it.
2. As far as diversifying bond purchases across time, nothing says you only have one bond/CD ladder, or that it is over any specific duration. Well, the size of your portfolio may say you have just one ladder or how many rungs there are to it. However, laddering is simply a methodology, to do exactly what you're envisioning - diversifying the purchases across time...as in months or years. As your maturities come, you'll be reinvesting and diversifying "across time".
3. The "purest" way to buy a bond ladder is in fact to buy it all at once. Again, you really do not know what will happen to rates tomorrow, next month, or next year. If we use your approach of buying the longest maturity first and then waiting on other maturities, you're likely taking the greatest risk. For the shorter maturities, you're missing out on yield while waiting. Is the additional rate increase you might get going to make a significant difference for a one year bond/CD? Not likely. However, on the longer maturities, any rate increase/decrease will have a bigger impact. If your view is that longer term rates are going higher, then your approach should be to delay those purchases. However, again, you need to counter that line of thinking with how quickly the long term rates will rise and the lost income in the interim.
4. By not purchasing the entire ladder together (or picking/purchasing individual bonds/CDs over a relatively short period), you are doing the equivalent of market timing.
5. Lastly, again, we really don't know where rates will go. Laddering takes the guesswork out of the picture.