To dddd.

I find that most Schrader valves I've used in the past few years have the rubber far enough up towards the end of the valve that it take a fair bit of pressure to get a pump head onto the valve far enough to inflate the tube. Then, to get the pump head off the valve requires quite a bit of twisting and pulling on the pump head. YMMV

I've never head any problem with Presta valve tubes and my washer adapter in a Schrader valve hole..

Cheers