Am I being too conservative in term of gears placement?

Falling "twice the distance" of the last piece is not very realistic, especially in trad climbing. 

It's 2x distance + slack + rope stretch + movement of the belayer. 

You're actually right. 2x distance isn't quite correct. I do place 20 ft apart when it's on easy scramble terrains. Not something I usually do on steep climb or potential falls. 

If you're placing the first piece 10 to 15 up, and then about 7 to 9 after, if you pop placing your second piece that's a high likelihood of a deck. Let choose 10 feet for the first piece. Climb 7 feet above, pop off. Fall down to 3 feet above deck but ropestretch, and where did your belayed stand?  Goodbye ankles. So maybe start being even more cautious? I sew it up, top to bottom. 

I also climb at the gunks. I dont see people placing their 2nd or even 3rd piece appropriately to avoid a deck (myself often included).  It's all risk management, to echo others. But I'd reckon many people dont know as much as they ought to, and its often poor risk management. 

I led laurel with its off the ground crux (6 feet up?) , and practiced the first few moves (getting 5 feet off the ground  then downclimbing) with my partner spotting 4 times. I placed two pieces as high as I could, came down,  had my partner stand with their shoulder on the damn wall to reduce rope in the system, and went for it. If I'd popped, I dont think idve decked because of my precautions, and if I hadnt felt confident after those 4 tries, i wouldnt have tried to lead, even with the precautions. Not worth my ankles. I've seen people lead it with their belayer 10 feet from the wall. If they pop before the 2nd piece, that's the ground. So those people must feel pretty confident, or maybe they're lucky. 

"The Best Climber Climbs Tomorrow" -GK

Gumby King wrote:

"The Best Climber Climbs Tomorrow" -GK

Well, that 100% fits the climber who only ever climbs onto a couch.

… no offense intended to couch potatoes.

 If I'm repeating a route or have tons of beta then yeah, I might run out certain sections because I know what to expect. 

On the flipside, if I'm onsighting something I don't know much about, I tend to be more conservative and place more gear because a crux can come up on you unexpectedly.  What looked like a nice sequence from the ground may be quite different up and personal.