One antispyware app with so called "real time protection is enough"
And MSAS is really good to real time protect your PC.
You also probably have a antivirus program running with RTP ?
These 2 programs also often "fights" with each other when the same
malware which both programs detects. But it is easy to handle.
If you have more then these 2 it will be a mess and also slow down your
PC.
For MANUAL antispyware scannings you can have several products.
Perhaps to check your PC once a week, MSAS manual detection is rather
basic and includes too many commercial "ignores", IMHO.
Lavasoft Adaware is then a good choice and CCleaner for junk removal.