I did not find that my VFR skills deteriorated during my IFR training --
although I did discover that my ability to maintain altitude and heading
precisely certainly improved. In fact, I became a sharper pilot all around
during my training.

I can honestly say that if I fly IFR most of the time. My VFR skills
deteriorate.
IFR flying is so much easier. I get vetors and clearances, if clouds appear I
fly through them. If it is convective I ask to deviate.
One reason why when going for my $100 hambuger on sunday I fly VFR. Other times
I file IFR.
Just my thoughts.
Hank 172 driver