I trade with IBKR... Yes, Overnight... This and more... The IBKR Developer Team keeps the LIVE TWS (live traders workstation execution software) in as best working order possible... considering how clunky it is for a world class top rated broker. IB Devs do updates every week on the LIVE. The SIM paper trader is NOT kept up to date. It has bugs and other sloppy problems. It works okay. I use it to test Equity and Futures Spread Trading Strategies outside my Live Account... But Sometimes market orders HANG and sometimes limit orders go unrecognized due to the fill engine server behind the SIM trader going out of whack.
You are assuming there is solid development efforts behind the sim. Give that TWS is in need of a complete rewrite, I don't think that is a good assumption. Also remember the weakest Devs (interns possibly) will be doing the sim version updates. So respectfully, I stand by the "random" delays statement. To be clear, not "random" as in "random number generator", but random as in a bunch of bugs layered on top of each other interacting. I have also experience the partial fill issue mentioned by rb7. Which leads me to believe any deeper interaction is incompletely spec'ed and coded. I only use it to see (with a grain of salt) how orders work at IB and never for testing algo code.
I don't think I have used a market order in about 15 years but I don't see what the point of paper trading is when you could just trade 1 share with zero commission. Something like PLTR comes to mind. $17.77 and you can just get filled for real.
I give you that TWS nor the server side doesn't exactly appear to be a pinnacle of software engineering. I once went back and forth with an IB support engineer trying to explain some pretty obvious bug in their API/server and all it came down to was "it's a feature not a bug" kind of condescending garbage response FWIW, I have 40+ years of software development experience and I can pretty well narrow down issues, and this poor sod thought he could skirt around it with some BS replies he has obviously used to dish out to avoid doing any fixes to the system. Edit: IB seems to have a new desktop app in preview: https://www.interactivebrokers.com/en/trading/ibkr-desktop.php
You can use DAS TRADER DEMO thats works fine. Or look at IBs Market Place for other front ends *Trading Platforms* or at IBs Third Party Intergrations and see if the Trading Platforms there offer Demos
I hear you. I am an ex MSFT test manager. So I too know how this goes. I think the bottom line is you *can* work on it, make it work, work around, but it is too far removed from actually trading that it seems like Dev work for its own sake. So I just left that morass and got my focus back on trading. No need to figure out their mess unless they are going to pay you for it!
%% On my cash metals business its always market exits[sells]; some holding copper if looks like an uptrend LOL. Good + practical, points even though paper trades are still a help, if say ,one knows PLTR + ETFs one trades/invests. Actually the way i trade + invest, a loss means the trend or med trend has changed, mostly , so a market ''time sensitive '' exit is best. Of course a standing order is limit, ''price sensitive'' as A Jacobson noted well. I use market exits about 80% of the time, mostly liquid , HI volume ETFs. And much prefer paper charts