As for timeframes for entries, if lower timeframes mean tighter stops, than as low a timeframe as possible so long as you can find a good trendline. In practice, I think the time available to sit and watch the charts may well be the determining factor.
Personally, I have less confidence in avoiding false breaks of trendlines on the lower timeframes such as M5 and lower. That is just an opinion and I don't have any statistical data to support my bias. I should preface my comment with a disclaimer that I am in the US and my observations are based on the NY session. It has been many years since I stayed up late to try and scalp a few pips during the London open.
I try not to fall victim to my bias because even if the lower timeframes do have more false breaks, that is not a negative since a trader can generally have a tighter stop the lower they go on the timeframe. That tighter stop should equate to less risk (in pips), which would lead to a larger reward relative to risk. A higher reward:risk would offset being stopped out more due to any false breaks.
As an example: Trader A shorted GBPUSD with a 30 pip stop, basing his entry on the H1 timeframe. Trader B shorted the same pair with a 15 pip stop, basing her entry on the M15. Trader B could be stopped out for a 15 pip loss and re-enter with the same 15 pip stop before she has risked the 30 pips that Trader A put at risk.
If both traders put the same % of their account at risk on each trade, Trader B would come out ahead as far as % return on the account. (Both traders exit after a 150 pip decline. The 30 pips risked by Trader A equated to 1% of his account, with his profit on this trade equaling 5% of his account. The 15 pips risked by Trader B also equated to 1% of her account. She netted 135 pips with her total profit on this trade equaling 9% of her account.) Like my wife, Trader B is one smart lady. Too bad my wife doesn't trade, she could have saved me many years of trial and much error.😀
These examples go back to Nigel's statement about using PAST to obtain longer timeframe reward (big) with shorter timeframe risk (little), which effectively multiplies your reward:risk. This supports using the lowest timeframe possible with a good trendline so as to minimize your risk and maximize your reward. And that is the best position for which a trader can hope.
Jonathan