How to write to gatt characteristic as fast as possible?

I have this so far, for writing as fast as possible to a gatt characteristic. The timing seems to vary though, and certainly the writing isn't 'continuous'. Is there a way to do better? I want to write 10 times per second, as stable as possible.

interval = 100;
function writeValue() {
    return new Promise(function(resolve, reject) {
        if (!isConnected()) {
            console.log("not connected");
            setTimeout(function() {writeValue().catch(function() {});}, 1000);
            reject();
            return;
        }

        char.writeValue(calculateValue()).then(f­unction() {
            setTimeout(function() {writeValue().catch(function() {});}, interval);
            resolve();
        }).catch(function(e) {
            console.log(e);
            setTimeout(function() {writeValue().catch(function() {});}, interval);
            reject();
        });
    });
}

I'm most familiar with writing in C or Python, so unfamiliar with Promises. I think I need to use them here, since if I simply call char.writeValue(calculateValue()) in a loop then often there's an error that BLE is busy (from https://github.com/espruino/Espruino/blo­b/31c67baa20302b80aafc5b355aade9028a37c4­71/libs/bluetooth/jswrap_bluetooth.c#L78­ )