Experienced users are an exception to the rule of too much security is overkill,
These Geeks would know how to identify processes which might conflict or run at the same time meaning scanning at the same time.....,
This would also depend heavily on the resources available on the machines not everyone has 8-... gig's of ram
As far as a sweet spot I believe I found that place,
The 3 I posted is mine but yes three is plenty if one would need more I'd leave that to the individual,
Just keep in mind all of these utilities update either automatically or on demand and often the updates have the possibility to be a bad apple
Even MBAM has had bad updates in the past so I wouldn't give any third party a hall pass on that possibility
The golden rule is how does the machine and built in Windows programs actually function,
If All Windows programs work then you've found a good combination
Usually Internet explorer would be the most effected program = Does it work ?
If not then one third party utility might be causing the issue,
Cheers.