When you're nearing the end of your rebuilding phase and ready to contend, you may decide it makes sense to sign free agents at some point. If you go after Type A's, try to time it so you do that the year after your team was still "bad" (if you have the 16th pick or better, you don't lose that #1 pick as compensation for signing a Type A - it only costs you your 2nd-rounder).
Also, if you decide to sign a Type A, it makes more sense to sign a 2nd or 3rd one in the same year, rather than one a year for 2 or 3 years. The Chaloupas this year are an example: 3 Type A's, which "cost" 2nd, 3rd, and 4th-round picks.
It takes some luck to time all this - you have to try to coincide your "go for it" year with a good free agent class. If you "grade" free agent classes by how many Type A and B's there are in it, this year's is so far a little better than last year's (20 A & B's so far this year vs. 17 last year). In my first year in Field of Dreams, there were 35 Type A and B free agents.