Comment by onion2k

A lot of alignment and pair programming won't be time expensive?

The question is really "Will up-front design and pair programming cost more than not doing up-front design and pair programming?".

In my experience, somewhat counter-intuitively, alignment and pairing is cheaper because you get to the right answer a bit 'slower' but without needing the time spent reworking things. If rework is doubling the time it takes to deliver something (which is not an extreme example, and in some orgs would be incredibly conservative) then spending 1.5 times the estimate putting in good design and pair programming time is still waaaay cheaper.