Years ago I used X-Rite DTP-41 photospectrometer along with Monaco "Proof" software on a PC workstation running a Wasatch RIP ( HP5500 w/o Postscript 3 RIP ). I didn't calibrate very often, only when we used a new media. What type of RIPs are you using? Are you running new media all of the time? Why not rely on past calibrations? Is the environment stable?
I'm using since many years Gretag-Macbeth ProfileMaker 5 with Spectrophotometer EyeOne Pro
for calibrating inkjets, toner printer, scanner and (experimentally) cameras.
This works very well, but the product is discontinued.
According to informations in the Web, a substitute might be X-Rite i1Profiler, Version i1Publish
with EyeOne Pro 2.
As far as I remember, Gretag-Macbeth had been taken over by X-Rite. i1Profiler is perhaps
based on ProfileMaker.
i1Publish upgrade, information in English:
Hope this helps a little.
Best regards --Gernot Hoffmann