You're a brave one working on 3 - 5 kits at the same time. That would be the ultimate mojo killer for me.
Maybe a little bit of perspective, and I did say it works for me but might not for everyone.
By "working on", that could include not-finished. Looking at recent items that need a little more before being declared done...
Unfinished
1/32 Corsair (need to finish the dash cover and gunsight, then add some mud/oil stain to the underside, attach antenna and wire)
1/48 Fishbed (need to finish decals, unmask canopy after clearcoat which is after decals, detail landing gear)
1/48 Spitfire (I found the antenna, so add it with wire and attach canopy)
Construction (these are what I meant about rotating around)
1/48 Lightning
1/48 Phantom-II
1/35 Bradley
1/35 M5A1 (way on the back burner, it made me angry once)
1/35 Merkava
1/24 MP4/4
On Deck (resisting the urge to add to the above category)
Three (!!!) 1/48 biplanes of Ernst Udet
1/48 F-19 Stealth
So I actually have 6 active builds, as in started gluing parts. On the Merkava, that is only a start on the two-part track links, the McLaren I've only primed some parts and assembled the engine block, the lightning and Phantom and Bradley are all in late stage assembly or paint.