I do Clomid/Nolva PCT's and I always run slightly longer than four weeks and I always recommend a nice taper for the SERM. I like to run Nolva out past Clomid for the extra protection against E2 (breast tissue). I see far too many people jumping off of their SERM but at a very high dose, eg. 50/50/50/50. There is also plenty of research on the combined use of Nolva and Clomid for PCT. It may not be necessary for lighter/shorter cycles but I would certainly recommend it for longer/harsher AAS cycles.
My last PCT (12 wk cycle) was very sucessful and I felt great the entire time. It consisted of...
Clomid: 25/25/12.5
Nolva: 20/20/10/10/5/5 EOD
TD Formestane: 50 EOD/50 EOD/50 EOD (50mg ED for a few days then 50mg EOD for the remainder of the 3 weeks of Clomid)
Arimistane: 0/0/0/75/50/25/25 EOD
I just started a cycle the other day that will be 5.5 weeks of LGD/Dermacrine, bridged into 6-7 weeks of PMag and Trest. My PCT for that cycle will consist of...
Clomid: 25/25/25
Nolva: 20/20/10/10/5
TD Formestane: 50 EOD/50 EOD/50 EOD
Arimistane: 0/0/0/75/50/25/25 EOD