[pclmulqdq]

Having a contracting period for senior engineers sounds like you must not get many of them. Most people I know at that level are swimming in offers when they go looking for work, so a contract period is just incredibly unattractive.

[lmeyerov]

Yes it varies. Some prefer it before jumping in, eg, super senior who mostly do advisory and light consulting. We are a small team so by definition each person gets more ownership than at your average bigco or megaround VC co.